Ebb,
The basic mold/form for the ports is pictured in post #124 on this very same thread. In that photo the holes have not been drilled yet. The bolt spacing/placement was determined and holes were drilled on the mold to act as drill guides so every port should be the same (mechanically, and in theory, of course).

The mix was a relatively loose mix of epoxy and cabosil with milled glass fibers(hate the stuff) and hand chopped roving fibers 1 1/2" to 2" long. What a MESS! The molds were clamped onto the previously shimmed and spot filled port openings. Then the 'mix' was added, poked, twisted, pulled into place. It really moved as one glob from the pot to the mold, and more than once I thought this is never going to work. I was almost scared to knock the molds off when it was cured. Thought for sure I'd be grinding the whole mess down and going with plan D or E. But I'm stubborn and did the job in managable stages.

The bolts are 1/4". I drew the original concept with smaller ( I forget the # size) but when I was standing in the aisle at the store I kept thinking these are way too small-I'll bend them trying to sand the filler.

There is a little bow in the openings. That's why I'm leaning toward a butyl seal. The stuff can fill iregularities with ease and it's not so bad to work with.

Sure wish I could get that high-build primer that you've been using. The local SW can't/won't get it.