12 Second N/A Slant 6?

Well, the concensus on V8s on cast cranks is 450 or so HP with a good balance job and a good balancer. Although I've seen people leave on the back bumper with cast cranks. lol I would think with those rods and the light KB pistons it would be light enough with the steel crank. I'm not sure I would want to risk it. You're gonna have a chunk in that motor.

If 450 HP is the threhold then W/300ish N/A HP & a 200 HP shot of giggle gas would be on the threshold or a bit above it.