Which K frame would you use, given the choice?

I'm in the process of building a Duster 340 from a complete, numbers matching car that's rotten out and two rolling chassis. I have both the 70-72 and 73+ K frames to use.

All things being equal (I'm using BBP spindles, upper arms and lower BJs either way), would you run the older biscuit style K frame of the later spool type?