\6 swap question

I am running a 1965 170 small crank engine, 1964 pushbutton trans, with the 1968 up front pump and input section with the V-8 four disc clutch pack. Converter is a 9.5 inch with the small snote and the large splines. This is in my 66 Cuda.
PS: It is NOT possible to install the low ratio later gear set into the 65 and older case, without major mods.