it is a magnum, I refer to the magnums as 5.2's and LA's as 318's

I guess the engine I am after is tons cheaper, its $1750 engine, trans, harness, and ECU.

I ran across an adapter plate to put a GM throttle body on one. So if the ECU can be hacked to recognize that, and not throw codes, I see that as half the battle.

As far as the Rx7 swap goes, the trans computer won't be a problem as I'll probably run a T56 behind it, if I can find a bell housing to do it.

I noticed one manufacturer had them, but also had 2 different bell's one for a LSx t-56, and another for a Viper T-56... which confused me.

I'd like to do the stock ECU if I could hack it, and retain the MDS..... as I think it would help with mileage on the truck.