i would go with the 3.73 gears with the taller gears you are bound to blow up the weaker trans

 

I think a 305 engine with 350 heads or 308 & 273 reverse 5-speed manual trans with an RV cam or something similar and go with a Holley carb and Edelbrock four barrel 500-650, Hooker headers 3 with a double master stream.