I wouldn't call that overstocked or even full by any means. I've always known Royal Grammas as peaceful fish, sure they will threaten other fish that get too close to their home with mouth wide open, but never really that aggressive.
I would also add the McCosker's wrasse early in the stocking order.
The Pearly jawfish might get into it with your Bi color blenny as they both live in the same part of the water column.
Like I said I don't think you're overstocked, here is what I have in my 40b
Cherub Angel
Pair Mocha Ocellaris Clowns
Midas Blenny
McCosker's wrasse
Royal Gramma
Yellow Candy Hog Fish
I plan on adding another fish and still thinking on which it will be. I really want a Starcki Damsel and still might get one, but still thinking on it. I might also get one of the smaller sand dweller gobbies if I can find one that I like, or one that jumps out at me
I had a Hector's goby and it was a great fish, I've had it for a year and then one day it never showed up for morning feeding. It was always very healthy and even ate NLS pellets like a pig. I can only think that since it was full size when I got it that it probably died of old age. Don't know for sure but that is what I think anyway. The one thing that I didn't like about him was that he would get a mouthful of sand and as he sifted it through his gills sand would land all over my corals and rocks. Too bad I can't get a fish like him but without the sand showers on my corals.
So those are the fish I have in my 40b with a 20gal sump.