Replacing Crankset on Vintage Groupset. Am I doing this right?

[Summer]

I have an old bike with a '93 Shimano RX100 groupset on it. Two of the chain rings are bent and rather than replace them, I'm thinking of replacing the crankset with this Shimano Acera FC-M361. (https://www.jensonusa.com/Shimano-Acera-M361-Square-Crankset/?utm_source=FRGL&utm_medium=organic&pt_source=googleads&pt_medium=cpc&pt_campaign=shopping_us&pt_keyword=&gclid=EAIaIQobChMI5K3qhLOx1gIVCyaGCh1YGwB8EAQYAiABEgJuLPD_BwE&avad=55963_a16c41e8d&rpi=41227&utm_medium=AVLK)

My spindle is JIS. I haven't taken apart anything yet, but after looking up specs online, I'm fairly certain my current one is 113 mm and the one on the new crankset is 122.5 mm. Is that something that could be a problem? Or is that exactly what the adjustable cup is for? This is my first go at any type of bike repair beyond the basic tire, chain, tube stuff. Am I on the right path? Are there any red flags that I don't see?

[BRMatt]

Hello Summer. The adjustable cup allows for very small adjustments in pressure on the bearings. A difference of 10mm or so between the old and new spindle length is far beyond the adjustable cup's range. You can try mounting the new crankset on the old, shorter spindle, but you're likely to encounter problems with either the inner chainring or the crankarm hitting the chainstay as you make revolutions.

You most likely are going to have to get the longer spindle. It probably is about time to replace the BB anyway. I suggest you consult our repair guides here at the site for help with the installation. Best wishes, and let us know how it goes!