As per my previous post, the factory-supplied levers are put together the same way. Maybe the epoxy they use for the over-the-counter parts is different (depends on the OEM supplier).
I've had several welded together using TIG and MIG, but not with OA gas. No reported problems.
We might as well delve further into improving the shift housing. Here's what I suggest (part DIY, part commercial plug).
http://www.seinesystems.com/ShiftHousBluPrint.htm
Sherwood