Deciding on a transmission

So I'm currently working on my first build and I have an engine to put in the car but i am not familiar with transmissions and not sure what i should put behind it. I want to put a manual but its not mandatory as the car did not originally have one. I just looking for something that will not break and can be easily rebuilt to perform better. planning to put it in my 71 scamp with a 5.7 hemi, planning on going for a street/strip kinda thing but also want to be able to cruise decent. Looking for any and all suggestions, tips, knowledge.
With this much motor, and the lightweight scamp, and the skinny wheel wells,...... A) you don't need a manual trans, and B) any automatic will do, so C) Stuff a regular A 904 in there and a 2800, and 3.23s minimum and call it done. ...... unless your Hemi has a big cam and lousy cylinder pressure , then add more gear, to get you off the line .