Hi guys, my first post so be gentle if I am planning something you think wont work

I have my 180gal set up at around 1.02sg at the moment. In it I have a ton of Cherry shrimp, A Sole, 7 BBG's, 1 Molly with a fair few fry, and a mixture of Nerite and porcupine nerite snails. Anyway, I am planning on adding more BBG's to around 20 and possibly 1 or 2 knight gobies, then a few F8 Puffers. This is my main question, how many would you add to this set up, 180gal, 6x2x2?
I know the smaller snails, and shrimps will probably disappear. I must have around 60-100 MTS's too. Also does anyone know of a good online delivery service that actually have these in at the moment because I cant find them anywhere.
Thanks for any advice in advance, Vinny