you can use the single port heads, but the combustion chambers are smaller-designed to have much higher compression than the supercoupe engine-higher compression on cast bottom end will lead to problems-if hes changing the heads then it would be stupid NOT to use the correct ones for the application-youll also have higher combustion chamber temps-and are a lot more likely to detonate as opposed to just bumping the compression down a bit and eliminating any possible problems before they begin.
as for the ac lines-they MAY be able to be bent, but i broke 2 sets doing so-and had leaks the one time they didnt crack-its easier, less hassle, and looks better to just get some made, but no point arguing-it just depends on how far you want to go with it-you might also note that i said "neither DIRECTLY fit"-which you cant dispute, as you said they had to be bent/drilled/tapped to fit yourself
as for your suggestion to just "use a front mount intercooler" how is that disputing what ive stated? I was simply suggesting that although you can use the mustang radiator, the sc one is far superior in fitment, allowing air to the intercooler, and it flat out outcools the mustang one. granted, a fmic is a good idea, but i thought we were describing swapping sc parts into the mustang?
back on topic-i cant stress how important a good tune is-although the stock mustang bottom end is weaker, a properly tuned engine wont kill it as fast as most people think-heck-theres guys running 10s on stock blocks pushing 20psi-lol