I don't think I'd do much re-designing of the port. Put some smoother corners on it, don't make it much larger volume-wise. Epoxy won't come off if applied to clean metal and mixed properly but methanol/ethanol will eat it over time so you need to protect it. Honestly I try not to ever use it...lol. But if you do this is ths stuff to use and it's not cheap: A-788 Splash Zone. It's a marine product from Z-Spar. If you're going to use it with alcohol then you need clean the head with acetone, then heat it to about 150° and brush on a urethane clear coat after the port work's done. You can also use the Moroso A+B but again, if you run ethanol mixed in the fuel (pump gas) it will need to be top-coated.