you would need pistons, rods, and maybe a block guard. no need for new sleeves or a crank. stock sleeves can handle about 500 and some change safely. and i have never seen a factory honda crank break. i have seen nitro funny cars crack a crank, but thats a totally different world, dotn worry about a crank.

your biggest concern will be a proper tune when doing 15psi and nitrous. i hope too run 18 and nitrous with pistons, rods block guard and a good tune