what to do 1970 chevy k20

[Chevrolet9279]

alright guys im at a point i dont know what to do.

working on this 1970 k20 i just got and i am finding all this stuff that doesnt match.

what does match:
frame
cab
tranny ( WHICH as a PTO i dont if thats good or not!)
motor

What doesnt match
rear end (corporate 14 bolt)
front end( has disc brakes)
front clip and body all excpet the cab

not sure what to do when i go get parts i dont know that to tell them
i cant say i got a 1970 K20 truck and get parts when i got differnt stuff on it.

i dont want to switch the rear end or the front end (im glad it has disc brakes) but not sure what to do... any ideas?? i think ill return it to a 1970 body but leave the front brakes and different rear end. AND the pto i wont use but kind of cool it has it.

thanks!