I would start by putting each cars needs on paper and and then comparing things cost wise. I tend to lean towards the purist side. And since the red car being a early 71' and is considered a series 2, I think needs to be kept with its original parts as much as possible. It seems to have had more attention than the white car. 240's in original (or close to original) are getting harder to find. Of course I can't see how much work each one needs, so I'm basing it purely on just the few pictures you've posted. It's just my opinion, but pulling good parts from the red car for the white car is kind of flowing backwards, so to speak, Others my disagree. You can sill source badging, interior and engine parts so why not just rebuild The white one has already been "changed" with the L28 swap and is already in need of a lot of cleaning up. I think you can more free to do more with it and not hurt the value. Both seem like a good starting point. You are very lucky. By the way, your spare L28 looks to be from a 78'