Mustang 4.6 dohc engine?
i know the sohc cost atleast $3-4k from autozone. Dont forget for the swap you need a wiring harness, computer, i believe different gauge cluster. It might be cheaper to swap in a 02-04 gt motor(99-01 had problems with spark plug blow out) which will drop right in, put a set of stg 2 cams and upgraded springs(needed along with a tune for stg 2 cams), longtube headers, and gears.
fodadddys right, it will cost atleast 4k if not more for the cobra motor.