Hello guys I need your help on this. I have been doing research and still coming up short here is what I want

I want my 1950 Chevy pickup with a 235 to be able to run 65-70 at decent RPM’s, but not lose good in town driving.

(I don’t have to have the tube drive and I want to run original rims 6 lug)

I know there are a very many ways to achieve this but I would like to know what you guys think is the best root to take.

A. Replace the rear with a blazer 3.08 with the sm420 open tranny.
B. Replace the rear with a blazer 3.40 with the sm420 open tranny.
C. Replace the rear with a blazer 3.08 with the T-5 open tranny.
D. Replace the rear with a blazer 3.40 with the T-5 open tranny.
E. Replace with something else?

If you guys have any great ideas or know which would be best or with is better than other it would be great. I am new to this and just don’t want to have to re due work because I have the wrong set up

Thanks
Curt