You definitely don't need to go larger on the fuel side than recommended. Most guys were "squaring up" the pills a few years ago, but now are running a spread, between 4-10 sizes bigger on nitrous side. Too rich will burn things up. That being said, don't stick a smaller fuel jet in it until you do testing on a chassis dyno or drag strip with a wide band O2.
Most important is a bulletproof ignition system. Close up your gap to around .032 and go a few ranges colder on the plug with an msd box or equivalent and a matching coil. For 100 shot, drop timing 2 degrees, for less, don't bother. Nitrous will find every occasionally misfiring wire or plug try to break your engine with it.
Only slightly less important, really it's just as important, is adequate fuel flow to the nitrous. Many drag cars have inadequate fuel systems that are masked by the reserve fuel in the bowls. You must have adequate fuel flow and pressure, allowing for system pressure drop and g-forces at the launch. While it can be done many ways, I strongly recommend a 1-2gal cell up front with it's own fuel pump and lines for the nitrous.
The last thing that's critically important on a nitrous car is the electrical system. Not a giant alternator, but system health. Nitrous is real picky about grounds. It also puts extra load on your wiring harness. Solder and shrink wrap your connections if at all possible. Definitely use quality wire and relays to power the solenoids. Clean and redo all the existing grounds on your car, then add another engine to frame, battery to engine, battery to body, and body to frame ground cable. Do all your connections with stainless bolts so they don't corrode. I weld a stainless bolt to the frame to bolt the grounds to.
I would possibly consider upgrading the valvesprings.
I think you can hit a 100 shot on a stock inlne engine in good condition for quite a while. But it will have a finite life, and you have to pay attention to the plugs and condition of system. Carry a spare set of plungers all the time. Additionally, one of those little propane torches to maintain pressure in the bottle the same every run. A scale to weigh your bottles all the time so you don't get surprised. If there's any question about whether something is right, abort and troubleshoot. I like nitrous but it can kill an engine very quickly in the wrong hands. Good luck!
