I bought a $20 eBay Tec carb last year for my H50, no problem.
I just bought one for my new to me H50. after a day gas started leaking bad from the area between the bowl and the carb body when the bike was tipped on its side. I took the bowl in my hand and turned it just a little bit and I did not force it, gas now came out faster when tipped.
I grabbed a box wrench and checked to see if the jet body that holds the bowl on was loose. it turned and promptly squeezed the gasket between the jet body and bowl into nothing and the gas came pouring out.
I had a Tec rebuild kit that didn't work on the old carb so I used the bowl and jet gaskets and the old bowl on the new carb and it was fine.
The H50 and HS50 carbs are a little different but not that much. Might be the same manufacturer?