On my wife's panasonic project, I am using some 27" wheels from an 80s model Schwinn 10 speed. I found out the Schwinn front wheel has a spacing of 91 mm and the Panasonic apparently has a spacing of between 96 and 97. However the 9 mm axle in the Schwinn wheel was plenty long enough and I can tighten the nuts down and pull the fork blades together. The axle happens to be bent so I need to go rummage up another 9 mm axle from another wheel today. But my question is would I be better off putting spacers on each side to space it out or cold setting the front fork together to redo the spacing down to 91?

The second question I have is the Panasonic fork does not have holes drilled in it for the safety tabs like the Schwinn fork had. Are there any certain types of washers that are supposed to be used under the axle nuts to prevent the wheel from slipping out or coming loose since there's no safety tabs or lawyer hooks?

Don't mess with the fork spacing or add any washers to the hub. Find a proper front hub.

I've never seen a front wheel off anything built from around 1975 on that wasn't 100mm. So, if you measure only 91mm then you're going to need to add spacers on the axle to get it closer to 100mm. I wouldn't be comfortable pulling the fork blades together by that much. It could stress the fork crown and cause serious problems. You don't your wife to have a bad crash.

I thought it was odd too because I figured these bikes would have a similar front spacing. So I googled it and on Sheldon's website He listed those spacings and they measured within a millimeter of what he said. This Panasonic was without a front wheel when I found it. The fork does not appear bent and everything looks straight and true but I suppose it's possible the front blades got squeezed together a couple millimeters at some point without the wheel in there. So maybe it's actually a 100 mm spacing?

Why no spacers? We're only talking about 2.5 to 3 mm per side? It's not like it's that much.

IMHO use spacers. Lot less risk and effort. Forget safety except for making sure the axle is secured to the fork. There is no reason for the axle to come loose if properly tightened, unless you are a lawyer.
I personally dislike any so called "safety enhancements" as represented by this feature. They represent abdication of personal responsibility. The root-cause of highest risk to lack of safety are people.

I actually agree with you but I just wanted to make sure. These older forks have the dropouts that sweep back a little bit instead of forward like some of the modern forks.

I didn't read your post thoroughly, yes, spacers are better than squeezing the fork blades

Awesome. I'm pretty confident there's no way I would find a hub to fit this fork over in this particular salvage yard I've been rummaging through. but I should be able to find a 9 mm axle and if not they're not that expensive to buy a new one.

First question: whether to add spacers or cold-set depends on how much load will be on the bike and how good you are at cold-setting, and by how much bother you'll find it to have to spring it back together anytime you take the wheel out. Forks are tricky because you have to get/keep two independent surfaces correct in 3d relative to each other and the centre-line of the steerer tube. The farther the dropouts are from the cones the more stress on the axle, if the rider is light this is less of a worry, and 3-4mm on each end is probably not much - plus you can likely reduce it by employing the proper solution to your second question.

Second question: yes there are washers etcetera, a good hub's locknuts will have a surface that bites into the inside face of the dropouts, and QR nuts usually have the same for the outside surfaces. Plain axle nuts are often supplied with toothed washers, either captive or free, for the same purpose. However, the best thing to do is this: Tighten those nuts like you mean it. It's what was done before the CPSC regulations came out.

Lol understood! I have experienced cold setting as I modernized an old Panasonic road bike and reset the rear triangle to 130. But that said I really didn't want to have to squeeze these fork blades together. I want to space the axle out but I just thought I would find out for sure what the best way was to do it.

Keep in mind that if you "squeeze the fork blades together" that the odds are very great that one blade bends a lot more than the other. Two identically-manufactured fork blades tend not to have the exact same yield point, at least in part due to residual directional stress imbalances in the metal that result from cold working (both before and after brazing).
It's even more pronounced with chainstays of course, because of asymmetric dimpling done to the right chainstay.

A good test of whether the fork spacing has been altered is whether a properly-dished front wheel has the rim centered under the crown, since any squishing down while the wheel was out will typically leave the fork tips off center. Then ride it of course, check if it pulls to one side. If it pulls to the right then the tire contact patch needs to somehow be moved to the right, either by dishing the wheel, moving the fork legs over, or perhaps even filing the dropouts (saved for last because it's irreversible).