Dyno'ed My 360..it's a pig..what next?

There might be shortfalls in your build, mismatched components, etc. But really start at the beginning. Get the engine tuned and running the best it can, pull every last hp out of it. Once it's running its best, then you can really narrow in on where its shortcomings are. And tweak for what you want out of it.

Or if you're after a number. Figure out what that number is. Then do what others have said. Pull it apart this winter and build for that number. Rather than throwing part after part at it, hoping to hit some goal of performance that you haven't set for yourself yet.