5.7 engine build

I doubt that cam will put you over 500 HP
Here is a Popular Hot Rodding article where they tested 3 different comp cams on the dyno. Power for the comp 268 peaked at 466
http://www.popularhotrodding.com/enginemasters/articles/smallblockshootout/0602phr_hemi/index1.html

It looks like you have a pretty strong combo already. I'm all for hemi swaps, but I think you would get more bang for your buck by stroking your 360 to add cubes.