I am putting a 1980 th 400 out of a 1ton chevy truck in my 64 ss.My question is what is the ration for first gear? and is it going to be siutable for my engine rear end combo?I am running a 383 with a edelbrock 600 with all the rods and needles fattened up so I can get the performance and the mileage.The cam I have in it the 510 488 lift with the 234 244 duration with 112 of separation. My rear end is a 10 bolt 308 gears .My tires are 255 50 17's in back with 245 50 17's in front.I know that I am probably goin to have to switch to a 750 carb.Any thoughts on a manifold? victor jr? rpm performer?...???????????