Had the good fortune of picking up some floor drain plugs from another T-16 owner that had them made. Good news, bad news...
I'd been using pipe flanges since they exactly fit the recessed holes. And electrical conduit 1" caps would fit nicely into the flange to allow for it to serve as a functional drain in each location. I'd epoxy sealed them into the floor so they wouldn't bounce out prior to installing bins and fuel tanks since I never thought I'd find anything that would fit per the original design.
Shot below shows how they looked from above on my pitted floor which isn't normally visible.
The problem I encountered is my own plugs were not intended for removal being installed from the inside. So now that I want to replace them, I had to remove the floor locker with battery and battery brackets, seat, seat bracket, locker that is mounted over the fuel tank, fuel tank itself after disconnecting the fuel lines, fuel tank holding box with brackets and the Bren gun spare barrel locker. All stacked up on my jeep and on the carrier.
So that I could spend 30 seconds screwing the proper plug into the floor from underneath as the designers intended. Last shot shows it in primer for reference prior to being painted and the joy of reinstalling all the removed parts.
At least its done properly now....