I replaced the coin door lights with automotive Sylvania #1893 bulbs. They are the exact same size as arcade #44 bulbs, but they work with 12 volts instead of 6. Everything is wired up and working, now it's just fine tuning and final touch ups. I updated the website, and added a Page6 with final pictures.
80s Man, thanks for the tip but I already have a couple extra non working Tempest boards that I just have to get fixed.