Which A727 to build?

I am needing to rebuild a 727 that will stand up to my new 408 that is being built by BPE. I have a running 1970 727 behind my current 360 and a stock complete 1973 727 I got for parts. Is there any benefit to building the newer unit? I bought the rebuild kit for the 1970 unit (bushings, seals, etc) some time ago, so perhaps those parts will work in the '73?