Go with a direct port kit. With forged internals you can EASILY spray more than 100 shot. I've known people to spray 125+ on a stock GSR/LS motor. It's all in the tuning. Piggyback ecu's are no good on the bottle, since they are generally heavy in timing. You're gonna need an inline fuel pump for when the nitrous is flowing, and you might want an aftermarket ignition if you don't already have one. I wouldn't hesitate to put a good sized shot on it, after all you built the motor right for a reason. Take the advice from people who know nitrous.