Well....if I have to do a top speed run
I guess I'll go try.
Damn I have to give it back in two days
I would have to rate this as a 5 wrench job. Rebuilding the whole tranny would be like a 10 wrench job, but that requiers alot of know how and training. The gear swap only gets you far enough into the 4EAT to make you scared of even thinking about having to rebuild the whole thing. If you can pull the tranny out then you could probly do the swap.
The only way this would save you from having to change gears later if you did a 5 speed swap was if the gears you put in the rearend are the same ratio as the ones in the 5speed you gona use. But after you do a 4:11 swap you want want to convert it to a manual anyway. It's like having a 5 speed but without all the shifting.
Cost of converting can vary, widely.