I bought a new 1" threaded 105 headset for my 88 Japanese Bianchi. I put on the cups...all good so far...go to put the race on the fork...hmmm its resisting. I take it to LBS and the guy says this is 26.4 and you need a 27 for your fork. Look in the catalog and see the Deore headset utilizes a 27 mm race. He calls Shimano and they tell him they are incompatible. My question is what to do now...

Remove cups and sell headset for a loss - I hate this idea.
Try the Deore race anyways - Risky and the the race alone is 14$ !!
File or mill the fork down until the 26.4 mm race works - I have no experience, hope someone else does
Drink a beer and stew

This is obviously my first time doing this, and I really wish the shop I bought this from would have at least asked if I knew there were differences...I would have measured the fork to make sure!

Find a LBS that can mill the crown race of the fork down from 27.0 to 26.4. This is a fairly standard procedure for a well-equiped shop.

fortunately I have access to a shop which allows you to pay per use their tool... a community bike shop. Any shop should have a stear tube vice thing. The goes in a bench vice... You can then carefully file the fork down to 26.4 using slow even strokes with the file and turning the fork constantly. I have done this to make a 105 headset fit on a schwinn premis. Didn't keep the frame long though as a Marinoni Special was sent from the big guy above.

Then you can drink beer and be happy!

Usually the headset cup size is different by 0.2 mm as well. This can cause problems.

Hmmm...well I already beat the cups on

Most shops can do that for you. I had it done to a Bridgestone 400 about a week or so. Not a big deal and it cost $10.

+1. This is the way to go.

If your shops aren't well equipped, or like me, you find this out Saturday night and can't wait 'til Monday, 36 grit sandpaper wrapped around a couple fingers works on the race, too.

I had this issue on the Volare. I turned the inside of the bearing race on a lathe so it was a nice snug but not press fit. No problems so far.

I'd always opt for the LBS route: the proper tool does a proper job and press-fit tolerance is fairly narrow and hard to achieve by filing or sanding. BUT, that said, I certainly have done it and since I learned the hard way that you can easily go too far and past the tight press-fit all the way to "sloppy": then your new best friend will be LocTite GREEN. An adhesive made just for this sort of application.

I'm opting for the LBS. Its already been 2 weeks since I bought it, and I still haven't ridden it. I am the most anal retentive moron ever. I buy a cheap bike and spend more on 2 stage automotive paint, headset, saddle, bartape, BB, tires, shoes, etc than the bike probably cost new. Least the time that the fork is in the LBS I can reupholster the $5 dollar fizik.

Is there a risk of getting it off center & then having the symptoms of a bent fork -- pulling to one side?