i thought i read somewhere a long time ago about those kits not being as effective as a plate type setup. i could be wrong and after seeing a few injected cars throttle bodies freeze cause the nozzle was too close to them, i would shy away from that type anyway. nitrous is pretty damn cold and theres no reason it couldn't freeze the butterflys being that close so i would opt for the same setup with a plate.
a stock bottom end can handle 300 horse max, but i would also say that 150-200 would be the reliable maximum. i had 100 horse to my stock bottom end in the camino last summer and there was no sign of wear, i am going to use 175-200 this summer. BUT, i also am not worried about blowing the motor cause its not a daily driver and 87+ stock bottom ends are not hard to find. lol