HOnestly speaking, it is just better to buy a superCoupe. I had a '92 LX and was thinking about the same thing. It has ended up much cheaper and I'm a lot happier with my SC. I even tossed the idea of a 351 in my '92, but the SC was cheaper by far. And I'm driving it now. I probably wouldn't be driving a T-bird right now, if I went for the conversion. Take your time and look around for a good SC to buy. They are out there and are a lot cheaper than converting your '90.