Still not 100% sure but I may go with an external overflow

My two cents, the best overflow system is at the end of the tank with the return at the opposing end. This gives you end to end flow with no dead spots, minimum friction loss and water is well mixed before surface skimming.

OK so it's confirmed. I'm going with an external overflow. That leaves the entire tank open for aquascape and lots of room for fish. Total volume with the sump is approx 400gal. I'm going to give the Jebao powerheads a try. The return pump is going to discharge into the tank opposite the power heads and overflow. Thanks again for all the tips and help deciding. Tank journal/build thread will be starting in the near future!

You won't be dissapointed with the external overflow. I love mine. It makes the interior infinitely better.