Sell it. Spend your time on riding, not planning a build, shopping for parts, disassembly, reassembly, and numerous tune-up rides.

I've built several bikes from parts, including wheels, and occasionally starting with a torch and frame repair, then painting, etc. So, I know the work involved in a proper job. You have a mint used vintage bike - it would be a shame to waste that with a modernization. Go over to C&V and solicit a value estimate, then auction it on eBay. It's the right time of the year to sell that bike!