I am getting ready to install a new closet flange on top of my above-floor 1964
fiberglass black tank. The old flange is long gone (thrown out during renovation), but I believe it was screwed to the top of the tank. The screws were mostly gone and were ground flat when the tank was re-gelled.
Can I drill and tap the inset cast metal fitting for new screws to attach the new flange, or is it better to glue the new flange on?
I am really trying to find out if there is enough (total diameter) cast metal inset in the fiberglass to drill and tap. I believe the process will be straightforward enough if I can ascertain if there is enough metal there to do it.
Thanks for any advice or insights.