The standard Oz for MT gloves is 10 Oz if you're following the standard of Lumphini.
Twins is very reputable distributor of MT equipment. I'd really recommend their shin guards and groin protectors. Mine's a bit old but it's still "nice and dandy". If you're going with Thai made gloves, get the ones from FBT, they're better. Twins have a reputation of cutting more than the FBT ones (I was hitting the sandbag with my twins gloves, and I saw cuts on the sandbag and on the gloves. Too much friction).
There are some american brands you can order, ask WildBill. I think Fairtex should be a good brand.