Check with the guiys over at the Ford six performance site.
On mine I have the low resistance wires, timing bump to 12 deg, spark gap at .050, and keep the oil and filters clean.
The big restriction in this engine is the cylinder head and nothing that you can plug in or bolt on will help much until you clean it up.
Electric fans can help but make sure your alternator can handle the load.
BTW your engine already has a CAI, and the stock manifolds are pretty good. High flow cats and a straight pipe out the side would probably help. Beware that some performance mufflers can make the 300 sound pretty strange.
"Nelly Belle" 95 XLT SC SB 300 4x2 5 spd 244k
"If women don't find you handsome at least let them find you handy" Red Green