John - I did a little research on the GM V6 (Camaro) motor after our call today.
2012-2015 Camaro V6. 'LFX' 3.6L aluminum motor/aluminum heads DOHC. It makes 323 HP @ 7200 rpm and 278 Lb-ft @ 4800 rpm. I couldn't find the weight on the motor but my guess is that it's lighter than the stock Boxster 3.2L.
I'll see if I can find some dimensions on the V8 so we can compare them to the LS. This could be pretty sweet build
I found the weight. GM claims 345 Lbs and Porsche show the boxster motor weight at 399 lbs. So, the LFX looks to be about 54 pounds less...