[nvrenuf]

I'd budget another $2000-$2500 and maybe even come in high. I think those heads are peanut ports which will not support that kind of power (read: $$ different heads $$). The real killer is the snowball effect where you start buying pretty parts or cool parts that evolve in to really cool parts.

I'm not saying it can't be done for $5k but to do it RIGHT with a dependable 600 hp combo, you're going to spend a lot.

I'd suggest sitting on the $5k and get the motor torn down and checked by a machine shop. Once they know what you have vs the parts you need, you can put together a realistic budget for that goal.