You most likely will have an idle issue with that cam, but a tune can fix that. If I may make a suggestion.......hold off on the cam until you get some better heads,gears, and a torque converter.
I had E303 in my 91 with automatic. i had no problem with it. I have E303 in my 95 GT with 5 speed and i have no problems with it. No tunes yet. I wonder why some people do??? i installed it straight up.