Glad to hear you went with #30's. I just read the post, hence I didnt get to give you my input prior to your purchase. Anyway most of the fast N/A 302 cars in TS and PS are running the #30's, so your 347 should need them. I would start them off in the 40psi range with the vacum line off. If you go wet system for your nitrous you dont have to worry about your injector size, dry you do. I used to run GT40 heads/intake, custom cam and ran the Bag of Nitrous dry kit with #24 injectors on a 302 with great results. Good luck to ya. Oh, check out
www.stangcrazy.com and ask some of them guys in the RS class what kit they recomend.