I am looking to purchase a64 savoy 2dr post as a roller it looks to have a 8.75 rear in it but it was a6cyl and the axel face has a nut on it?? can I change this to a newer style set up?? And what about the tranny it is a push button ? can I use a newer style 727??

Yes, it will have an 8.75; what you see are the ends of the tapered axles. I think Dr. Diff (member) has parts to change those for the more modern ones, or just use a later B rearend depending on the width/wheel/tire you want.
It will also have a ball & trunnion at the front of the driveshaft instead of the later U-joint.
Push-button uses a different mechanism than '66-up cars, '65 is a 1-year-only that kind of bridges the 2 designs. Ask CRT or A&A about specifics. Both are members here. Note that the cases differ between engine families.
There's nothing "wrong" with any of those original parts for a street car; back in the day guys raced with those parts. That said, I changed all that out on my own '64...

65 to 70 rear will fit.65 to 67 are a bit narrower than the 68 to 70s but they fit.I have a 69 in my 65 B body.As said the trans is push button.with ball and trunnion drive shaft.You will need an early trans or convert to a linkage style.If its a /6 you will need motor mounts to adapt a V8.Rocky

Thanks guys I just need some basic info to startand figure out witch way im going, Ihave v8 k member and might go 4 speed .