I'm new to the bike scene and wanna buy an older vintage bike and fix it up. I'll be doing some triathlons in the future and would really like something that I can use in this setting. Something that's not too heavy, I kind of like the idea of a steel frame but would like to stay relatively lightweight if possible. I also want to upgrade the components to more modern stuff, most importantly the shifters. So, with this information what should I keep my eyes peeled for on craigslist? I saw a 1988 Centurion Ironman yesterday that looked like exactly what I'm looking for but someone beat me to it

Thanks