cobra or mach 1 onto a gt motor?

Just food for thought.....

As much as it would end up costing you to purchase a 4V and swap it in, you could go FI on your 2V and get a hell of a lot more performance out of the car.
 
You could do a head swap, but in reality it'd be easier to drop the entire 4V engine in place of the 2V.

Exactly, and IIRC the 99+ 2V pistons have a larger dish than the Cobra and Mach 1's (excluding the 03-04's of course). Therefore with 4V heads you'd lose some compression... and that's no good...

Just food for thought.....

As much as it would end up costing you to purchase a 4V and swap it in, you could go FI on your 2V and get a hell of a lot more performance out of the car.

Exactly. If you're dead set on going 4V, do what StangGT said and install an entire engine. If you just want more power, cams, exhaust, headers, and a tune would get you damn close to a 4V car for considerable less time, money, and effort than swapping engines would.