setup im looking to do in 49 truck. opinions?

[Midgets50]

if funds are all right im gonna invest in a 4bt cummins and use my 1 ton 79 axles 4x4 axles. unsure of tranny i know a turbo 350 will mount to them but might have to do some looking to see if a 700R4 will work. gonna put 20 in rims with 8 bolt pattern and put some military grade tires on it either humvee tires or gonna run the duece and a half tires. then im gonna have a local shop build me a 50 gallon fuel tank. any input on what you guys think. any ideas on how to improve or change around