5.3 ls with th350 questions

[bd blk 12v]

Hello guys i just purchased a 5.3 ls taht im going to swap into a 47 chevy ad truck. I dont have a transmission and am looking at what to buy. The truck was a 4x4 that i got the engine from. Im just wanting a nice cool cruiser. The 47 has a 10 bolt rear end. Im not sure on ratio. Would a th350 be an ok choice and maybe a 3.42 ratio? Would it be better to have an auto with overdrive and spend the extra money? I have access to a th350 pretty cheap and plan on a cam swap possibly on the engine. Thanks