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...I have either rehabilitated, overhauled, or "restored" from the ground up at least a couple of hundred bicycles. One of the most valuable things I learned in all of that is that it is a mistake to buy anything before you have the project frame in hand, and disassembled. On your question about cranks, the different square taper ones all have a recommended spindle length. The newer ones, with various configurations for fitting the crank arms to the spindle are more standardized, according to whatever crank you are trying to fit to the bicycle.
It's good you have the work space. Spend your time building yourself a small workbench in there, figure out what you are going to use for a work stand, if at all possible, solidly affix a decent bench vise to your workbench, and budget to buy some tools for the different bike specific operations that are involved, in things like pulling and installing cranks, and removing and reinstalling headsets. etc. etc. It's not the cheapest hobby, but it's less damaging than drinking and whoring.
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