Originally Posted by jemaleddin

So, there's a lot of information in the replies, and instead of responding to everyone, let me just tell you what I did.

• I put a set of 105 indexed 7-speed shifters that seller gave me for free on, and they work great with my 7402 rear derailleur.
• I put on my FC-7410 52/42T cranks/chainrings and they also work with my shifters (I mean, it's just friction, so why not). The chainline is totally fine with the cheapo BB the previous owner said he put on (don't know the specifics).
• I left the existing FD (a 7800) in place because my 7410 has the wrong clamp size. I would love to swap them because the 7800 is a little corroded on the outside, but alas.
• I tried a bunch of things with the rear wheel: it was a 6-speed freehub, and a lot of wheels set up for 6 can also accommodate 7, but only if it is actually set up for 7 and you've put on a 6 (AFAICT). I found this out by buying a SunRace 7-speed freewheel, finding a Regina USA freewheel tool to take off the existing one, put the new one on and watched as it very gently rubbed the inside of the seat-stay above the drop-out. I then looked into relacing a wheel I had that was set up for 8-speed, finding a 7-speed freehub body, etc. and then found a nice vintage set of matching wheels that I got cheap, and put those on with a new Shimano 7-speed 11-28t cassette which works and shifts wonderfully with the rest of the gear including the existing (no wear so far) 8-speed chain.
• I tossed some nice 25mm Vittoria Rubino Pro Control tires on the wheels and they're comfy and great.

Here's the current setup when I took it out for a ride today - please ignore the super long valve stems, it's all I had that would fit a 25 at the moment.



Anyway, thanks again for all the advice! I may make other changes in the future, but for now it rides great!