[63sbssbbw]

Welcome to The board Mr B
I would strongly suggest either the '63 or the '64 chassis as interchange with later years
(up to '87) is much more feasible,cheaper,and available at your local parts store if you plan on any upgrades,ie disc brakes,power steering etc.
Strange as it may seem,the '60-'62 front suspension parts are about 3x the price of the '63-'66 pieces.
If the '62 cab is the best one, use it .
Your only change will be the front cab mount location,but you'll probably be doing floorboards anyway (just order the '63-'66 pans).
The wiper motor will have to remain as '62,but the heater is an easy mod to get the '63 one to fit.
Again,welcome the the site.
Tons of very knowledgable folks here in regards to this series of Chevy/GMC,and always willing to help a fellow 60-66 nut out when the need arises.
Trent