if you want a 3.8, your best off to take the mods off your car you have now and put it back to stock trim. Then sell the car and buy a GT or GTP and put your exterior mods on that. That would be cheapest. Especially since you are spending lots of money to basically turn it into a GT/P with the rocker panels and HUD.
I never said my parents SE, I said YOUR SE lol.