no you can do high ratio roller rockers. personally i recemend rollers. but go to high and your gonna need valve springs also. i think its past 1.84 and you need the springs.

you can put a gt transmission is your car, they have the 3.29 gears, or you can pull your trans apart and make the change.

stock, to a 3.4 set up, yea its gonna be a big difference. it will still be very dd.