When we first got our "87Trike1200" it was already converted and served it's previous owner well. We knew the former owner and I acquired it for Barbara when he upgraded to an 1800. At the time we got it, like you, we tried to learn more about it with little success.
All I can tell you is that for us, and the previous owner, it has stood up to the "test of time" and, unless you have a particular problem, I would not be concerned by it being an "off brand".
At the time, my '95 1500 was a 2 wheeler which was later converted by a very competent Motor-Trike dealer. He mentioned in passing, that should we ever have any problems with the Tri-King, chances are he would be able to help. As it has turned out, so far the only problems we had with the '87 was with the "famous" Honda 1200 alternator. Other than that (nothing to do with the Tri-King conversion), it continues to run strong.
Best wishes with yours...