the 63 was never designed for a V8 so there's a little more fiddly-ness to get a V8 and 727 in there.
the seam in the firewall with need to get flattened out to fit the 727 bellhousing. along with some massage work on the upper wall near the heater/wiper bump out.
you'll need to change out your rod operated accelerator pedal and linkage for cable operated. cut the trans cross member to fit the extra pipe for the V8 or run it as a Y ahead of the mount. at that point i'd just poke up thru the floor and run a aftermarket shifter for the 727.
exhaust wise, good headers are gonna be loot (dougs, TTI) or the sanderson shorties should work-- i'm not 100% of fitment with a 727, but they do with 904. or, some combo of exhaust manifolds, ideally stock V8, but likely magnum mix-n-match or some such.
you'll need to update the radiator to match the in/out of the waterpump (lower hose) and upper hose (t-stat). you may need to swap the oil pan, depending on what you've got on there.
PF is correct in the K member's being the same. and yeah, you'll need mounts and the dropped centerlink.