So I have an MS4 with milled 2.5 tsp ls6 heads the car puts down 420rwhp on a mustang dyno. I was planning on running a 383 rotating assembly and a fast102 intake. I figured this would cost about 4000$ and would put me somewhere in the 500 to 525 rwhp range and would be a optimal 383 set up.

But I started looking and it seems I could go with a 418, and reuse the same h/c I have now for close to the same amount of money, about $4800. I understand this isn't the optimal set up for a big cube motor but I figured it could get me relatively close to the same hp level with a lot more under the cure power and a lot more room to upgrade later on.

The only combo like this I've seen is CuNfUzEd's hellblazer with a 402 with stock heads and cams and he made ok power

 

I don't think the fast 102 will bolt up to those heads, double check that, I could be wrong.

But... it should be a pretty good setup for either the 383 or 418. To be honest, you are probably going to get diminishing returns upgrading at all. But of course, there is a little bit more power to be made with a more optimal setup.

 

I want to hit it with a 200 shot and the motor already has 110,000 miles on it. that y I want to go with forged bottom end.

and all fast intakes are 102 now, they have one that works with ls6 style heads