[LS6 RAT]

This would be a tough choice. Two distinctly different style vehicles. There are some interesting differences in the two engines. The Camaro version uses different exhaust style manifolds and air cleaner housing assembly. It technically was never called an LT-1 designation, as a matter of fact, Duntov used to cringe when people referred to the Camaro powerplant as an LT-1.

I personally think that the LT-1 Corvettes are undervalued at the present time. The way Chevrolet marketed the package, it came only with manual transmission, standard with Transistor ignition and 2.5 inch exhaust, in Corvette form, for years '70 & '71.

I also think the '70 thru '72 Camaro Z28's are becoming increasingly popular with muscle car enthusiasts and that finding a pristine original might be getting very tough to locate.
I would think this decision would come down to LOOKS, what body style gives you goosebumps, I'd let your heart talk to you, then take the plunge, whichever one you pick, I'll bet you'll have a lot of enjoyment ahead of you!