Small Block & Big Block Chevy Specific - big block street car tranny?

I am wondering what transmisson to help highway travel and lessen the beating on the engine from high rpms. I currently have a th400. Should I add a gear vendors unit with gets like .78 final gear or get a strong 700 hp rathed t56 that has the .50 final gear ratio

T56 if ya want a manual which what I prefer but if you like autos might wanna see if a 4l80 I think is what its called its a 6sp auto at least but anyways see if that'll bolt up add a stall

its not exactly the fact that ones auto and ones stick. I can drive both. just curious if getting a t56 over a gear vendors unit is worth the trouble to gain some mpg and help the engine on the highway. or just slap in a gear vendors :)

its not exactly the fact that ones auto and ones stick. I can drive both. just curious if getting a t56 over a gear vendors unit is worth the trouble to gain some mpg and help the engine on the highway. or just slap in a gear vendors :)

4l80e

Lockup + OD better option than GV

What is the best place to find that combo tt496?