Heads

I own an 03GT and am thinking of buying a set of 96-98 Cobra B Series 4V
heads W/Cams. Will this fit and would it be worth $300? Also is the 75mm BBK throttle body, will this fit and work??

4V conversions cost way too much to be worth it. Considering you need heads, timing components, intake manifold, fuel rails, coil boots, etc. Also, unless you are going for a full race only engine, stay away from B heads since the port volume is way too big for a 4.6 and you'll have nothing down low. Instead, stick w/ some ported 2V heads or a 3V conversion. If you're set on 4V, get any 99+ tumble port head (99-01 Cobra, 03-04 Cobra/Mach1/Maurauder, FR500, or Navigator).