I had also picked up a brass nut and threaded valve stem to braze onto the steel tank if the insertion of the valve stem went south. Think I'll bring it all back for a refund.
Yeah buddy !!! Glad to see you solved the issue. It reminds me of replacing fuel lines on some of the chainsaws.... you absolutely SWEAR there ain't no way that fat adz fuel line grommet it gonna go into that undersized hole in those plastic gas tanks !!! But you described my process perfectly...except for the squinty eyes, skewed tongue positions and the depletion of the expansive volume of expletives at my disposal..... ...but I do use a little two stroke oil on the grommet first though.