What to build 63 GMC or 66 Chevy

[cooperhw]

Kinda dumb question for you guys with lots more knowledge on these year trucks but here goes.

I am trying to decide which truck to build. I bought a wrecked 66 chevy longbed, practically no rust just bent frame, front fender, etc. and while looking for a frame to put under it came across a 63 GMC shortbed with a little more rust, no bed, but also a good buildable truck.
Am I to understand that the 66 would have more legroom? I really dig the look of the wraparound windshield on the 63 and these really cool original side mirrors (small square units).
Anyhow, I am a muscle car guy and pretty knowledgeable about those, but these years trucks I am a Newbie for sure.
Hope to start learning.