Options for 2x9 brake/shifters on 90's build ?

[vcballbat]

Ok, don’t do that ^

Make your life easier and use:
-8-speed cassette with 8–speed shifters
-9-speed cassette with 9-speed shifters
-10-speed cassette with, well, you can see where I’m going here.

You can’t use 10-speed shifters with an 8-speed cassette. The pull ratio is the same, but the gear spacing is different. It won’t index. But, @vcballbat a 10-speed cassette will fit in the same space as an 8-speed so you could just switch to a 10-speed cassette and it’ll all work correctly. You might need to swap the chain too because I think 10-speed chains have flush rivets to clear the tighter spacing

I built the bike up with parts I already had, the eight speed option was originally chosen because it's cheaper to replace worn chains and cassettes. With the cable pull hacks I've got the option to run 8, 9 or 10 speed. Not yet tried a 10 in the frame, could be some clearance issues with the horizontal dropouts

 

[sjcprojects]

If you're going down the STI route, it's likely to be either very expensive for decent condition 105/Ultegra/Dura-ace ones, or you're going to have to be very patient waiting for the right ones to come up on eBay for a reasonable price (also that era of 105 was with the big yellow '105' writing, so not the nicest anyway). Going the downtube shifter and new brake levers route would be a lot easier, I would think.

 

[pigman]

Or you could do a bit of mixing and matching. For example, campag 10 speed shifters work perfectly with a Shimano rear mech and a Shimano/SRAM 8 speed cassette