do a search for 351w swap and you will find alot of information on it. also if you look for pokageek's pain thread that particular one has a good bit of information.
sorry i dont mean to highjack but why do the highport heads have header clearance issues? i was looking at those instead of the AFR 185s. do the afrs have the same issue?
The TFS High Ports make header selection nearly impossible because it's hard enough finding headers for them with a 302, let alone 351 swap headers for them. AFR heads would use any standard SBF header for the Mustang.