I spoke with Taka over at Kyusha House, very nice by the way, and we identified the manifold as a Mikuni. Even though there is no stamping, Taka let me know that there are version with and without stamping. I opened up one of the carbs to get a better idea of the inside condition and luckily it was not bad at all. No jets appeared clogged and there was no gunk in the bowl. I think (and hope) an ultra sonic cleaning will suffice. From there I would like to get all of the hardware plated so I will be researching recommended places to send the hardware off to. Also, it is nice that rebuild kits are easy to come by. Even the diaphragms are available which I will replace just in case. The jetting installed looked to be the original jets and choke size, so I will start with these and see how she runs.
I will take a break from working on the car during the holidays, so I have been playing with Fusion 360 in my spare time. I came up with a simple velocity stack design, 100mm long. No idea if my initial radius are optimal, but its an easy change. I tried to maximize the diameter of the trumpet without causing interference with its neighbor. The flange was super easy to create! Up next will probably be a throttle cable bracket as I am missing that piece on my first carb. Everything will be printed in ASA, which should have enough heat tolerance for this application. A heat shield under the carbs will also be used.