the custom cam is going to have different ramp rates, and duration than a typical cam, it's going to be "made" for your combo...why not take full advantage of it?
partially right, they're going to tune it for the highest number-but, a reputable shop will also to tune it for the least possibility of detonation, i.e. fuel curve-which once again, is much more critical on power adder engines...didn't he say he was thinking about running a supercharger? And like i said in another reply on another thread, just cranking up your fuel pressure, and bumping your initial timing will not always give your particular combination the desired effect.
last time i ck'd Mustangs don't have knock sensors, so advancing your timing where it runs best will sometimes not play too well with computer determined advance curves...and sometimes dropping the initial advance will not cure your midrange or wot detonation problems, and even if it does, then your initial timing is so low that it runs like a$$ on the low end...
we'll agree to disagree on this one, I can see where you're coming from though, since you prefer N/A, there's rarely a huge need to tune unless you've changed so many variables that the car can't be satisfactorily adjusted with just initial timing and fp tweaking.
tx: If you want to run a blower, go for it, just keep the combo reasonable, and it will still make great hp...there are people on this forum who are pushing close to 500 whp (or more) with a boosted 306...even a 500whp N/A 347 is going to have some mild drivability issues
If you go N/A, I suspect the general concensus would be to go stroker-dependant upon your expectations. If you only want to run 12's, then a little 306 with an average supply of bolt ons, and some chassis stiffening would be fine...