The short answer is yes... BUT, you'll need a lot to make it work. I assume your 4.6 is a 2 valve and not a 4 valve so I'm not certain if you'd need to convert to hydroboost for the brakes or not, or possibly just make them manual brakes (yuck). You'll for sure need a new K Member that will accept the engine mounts for the 4.6, and likely a new transmission cross member. You'll need to completely rewire everything and will need a new (likely custom) driveshaft and custom exhaust made for it.
In the end, you could have it upgraded to a V8 but the cost won't be cheap and it will not have anywhere near the value of a car like it that was swapped with even a Mustang GT 4.6 2V with the PI heads and intake and a 5 speed... I'd say for this one the juice isn't worth the squeeze.