If it's a BSA threaded BB with a 68mm bb shell. I'd go with a 2 piece crankset. Most likely Shimano Ultegra will be my choice. Square taper is a little long in the tooth and old stuff. And I'd get all new or NOS stuff for the frame whether the frame is new or not. And I'd probably do Di2.

This is a frame from the early 2000's isn't it? Unless you want it to be a period correct museum piece, it matters not whether it's a 4 or 5 bolt crank spider.

I'd build the frame out for me. I don't care about resale. I tend to give away or sell my old stuff for a pittance. I'm happy that someone else will get use of them. It's not a investment to make money from.