do the top swap. top swaps on gt's are supposed to be like 5% faster or something like that because of the gt's higher gear ratio. then for a built tranny get a getrag 284 and build that so you can have fun with a 5 speed
As a guy with a Getrag 284 swap, I recommend it to no one unless you know 100% that the trans is good and you have access to many different things for fab purposes. If the trans blows, good luck finding another.