Thru - hull leaks

[Insufferable]

This MUST have happened before. My '78 sceptre is taking some water through the deck drain through hulls. It got past the caulking, rotted through the backing block and voila, its in the bottom of the boat.

What's the best thinking on these through hulls? The plastic part is cheezy and scary. I can seal up the wood blocking with some epoxy, bury the little plastic things in a lot of 5200 and hope for the best, but I'd sure rather have some bronze threaded parts that put some pressure on the caulking. Any thoughts? Thanks in advance.