I've done somewhat the same, except in a JR7-D and I kept 4 JJ's on it. I call it The Tiny Poptart. Still an experimental build tho...
I reduced my armor down to 215 to squeeze in a JJ and run with 1 PPC and ERPPC for a little heat efficiency. This build is hilarious when running in a light pack. Pack keeps target occupied while you open up the armor.
2 PPCs are better. As a light, you shouldn't have problem pulling the distance to 90m. This gives you a lot more shots before you have to bug out
Rated OP as crap, linking the proper setup's thread. http://www.mechspecs.com/forum/index.php?topic=3540.msg21325#msg21325