I was going to swap my B heads to C when I did my rebuild but decided not to because I wanted to get it back on the road fast.. lol.. a year and I still have the engine and trans out, but they are rebuilt and ready..
I have 99 navigator heads and an 04 Aviator intake I was matching up and welding a larger TB plate on when I decided to just go back to what I pulled out. The guys a Sulivan Performance said that the B heads are better street than the C but the C heads tumbled air and produced more mid-range torque. They convinced me to use the 5.4 navigator heads, which bolt to the block but the 4.6 intake won't fit without some modification since the ports are larger on the navigator so the intake needs to be welded a bit and opened up to keep from an air leak and getting a good port match.
Sullivan told me all engines that came from the romeo plant had forged internals as well, and that all 4v engines were built there but cranks were special for the Lincolns. Not sure what that means exactly though. I know my 4V came with a 6 bolt crank ( doesn't look forged but Who Knows it looks real nice if cast but has a thin parting line), also an aluminum block and cracked rods with floater pins and hypereutectic ( I think, very smooth and light ) pistons. Mine is a 95 not sure what the different years did.