8 3/4 transplant into my 66

So measurement wise is the 67 and up 8 3/4 shorter drum to drum, than 63-66 factory axle, if this is so is this made up by using a positive offset wheels? Also on the driveshaft, I have a 64 Valiant, 318 with an OD manual trans, I used a driveshaft from a 77 Volare automatic car and it fit with no modification...........