Quit screwing around and yard an entire 429/460 drivetrain out of another truck. I bet you could get the whole shebang for under $800 with a little persistance. Of course that depends on where you live too I guess..

Otherwise.... I agree too. The 300 I6 is the better way to go for grunt. Especially with the readily available aftermarket stuff for them. And look... you'd save the cost of boring and finish honing on 2 cylinders....annnnnd only have to rebuild 1 head rather than 2!!!