Try this....
Although I am sure you will get many responses, here is my . 02.
Start with some DD1's or 275 injectors and then an EZ box.
The injectors will add fuel where the EZ box doesn't so much, and vice versa, so it makes for a really smooth powerplant response from low RPM on up.
Additionally, make sure you use the boost elbow with the EZ box to give a little bit more Boost pressure to keep the EGT's in check.
IMHO, this is pretty much all you could really get away with before you have to upgrade the 5 spd clutch etc. Any more and you would be really pushing your luck.
If you tow, this makes for a FINE towing combination, as EGT's never get too high, and the power is awesome.
BUT, do put in guages. It took a while to finally sink in that I need them, but now I realize with the upgrades, you will want your peace of mind.
Shawn