If the bike is early 80's it would be friction shifted as SIS started in 86 ( 85 for Dura Ace ) and you would need to change out more then just the crankset. I know RSX had 7spd STI's but not sure on 105 as I have only had 8spd & up STI's in 105 & 600 tricolor. I had a problem running 8spd STI's with cranksets that had non SIS Front rings, I installed 9spd rings & everything worked perfect. You would need to change the Freewheel or cassette to SIS along with the chain, RD and install modern SIS shift cable & housing.


Glenn