Potential, cost, porting options, etc.

PS..

I have already read the info from the RHS site about these, just want more real world info, porting cost/benefits, valve size upgrade needed, how big of lift cam can be used, etc, etc.....

69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, low 10.30’s 1/4
1.41 best 60 foot
6.56 at 104.17