You can buy one already set up to handle a lot of power or I guess a transmission shop could do the same thing. A 460 has a lot of power but will fit tight in your bay. The Mustang won't handle as well with all of that weight on the front end. A 351 Windsor can be stroked out for a lot of cubic inches and with all of the aftermarket parts it can be made into a great performer. It is also a lot lighter than the 460. Another route would be to stroke your 302 to a 347. They can also be built to have amazing power.