I have a brother that wants to set his 65 Chevy truck step side to get as much gas mileage as a VW:3dSMILE: .He is wanting to put a straight six,and a 700r4, will this combo bolt up fine?I am thinking 350(with proper compression and cam) with the 700 set up for best fuel economy.Will a 283,327 be better on gas mileage?