1950-1954 Chevs, which would you choose and why?

You can't go wrong with any of those years. It's a matter of what you're attempting to build (custom, street machine, gasser ?). The 49-52 Chevy's make great customs, especially with the fastback roof designs. But they can look great as street machines and gassers with the sport coupe roofs. The 53 and 54 Chevy's are a little boxier and can be more difficult to rework as custom's. But they make great street machines and gasser's. The mechanical's may not make much of a significance if you plan to change them out anyway. Currently I own a '51 and '54 Chevy. The '51 is lowered with a modified 235 and 4 speed. The '54 is a street freak with a 7" lift; steel tilt hood; small block Chev setback 50% and Olds rear end. I wouldn't give either up. You've chosen a great group of vintage's to choose from.

Parts can be had for all 49-54's through either Chev's of the 40's or the National Chevy Association web sites. Here's their links.

http://www.nationalchevyassoc.com/
https://www.chevsofthe40s.com/index.lasso

Good luck with your selection.