Again, I'm facinated by the way the responses go off on a totally different tangent, effectively ignoring the original posters question!
Obviously, he has a rather limited budget to work with, so I would have to assume that if he can't afford the $6500 price tag of a brand new, fully forged, Aluminator crate motor, then a $15k Cobra probably isn't on his radar either.
Used, or refurbished, complete 4 valve motors from a Mach 1, Marauder, or Lincoln Aviator, which are all basically the same, can be had for anywhere from around $2k to about $3500, depending on mileage and condition. Used to replace a blown up or otherwise trashed stock 2 valve, they would provide a decent power bump, with considerable future potential, but unless you are doing the swap yourself, the labor costs might make the whole thing a little less attractive.
2003 Torch Red Ford Mustang Mach 1 5-speed
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