Found A '91 Notch 4cyl, 5-speed How Bad Is A V8 Conversion?

keep looking

Agreed. By the time you are done swapping over everything and the price for two cars, you could have bought a V8 notch. You need to pretty much swap the entire drivetrain, brakes, suspension, harness and then you still have a car that is titled as a 4 banger when you go and try to sell it, which people will always question if it was a hack job or not.

cheaper insurance for a 4 banger but unless your giving it to a 16yr old as a car, probably not worth it.
unless someone gave you one of those cars

Just about the only common parts between a 4 cylinder Mustang and a 5.0 is the body and upholstery. Almost everything else is either 5.0 or 4 cylinder specific. You end up buying two cars and stripping the 5.0 car for parts to put on the 4 cylinder car. Not worth the effort unless you get both cars in excellent shape for $500 a piece, and have a shop with all the tools needed for a complete tear down and rebuild.

I converted to my current 89, and I would not do it again - it's too much work. Here's a link to an article I wrote shortly after doing it. http://mr5oh.tripod.com/4to8.html