Looking at the first post and the 250 - 292 intakes I am used to, no gain could be had with port work. You need to start at the valve seat and work all the way back to the carb base. Then you risk the chance of opening the port to much which will slow down low rpm air flow. Size is just as important as flow, maybe more, bigger is not always better. Limiting the to two center ports would be a better way to go. One could also look at the exhaust ports on the outer cylinders. If you can get the exhaust out faster, then you have more room for fresh air to come in.
I have a ported 250 in the basement with exhaust ports that out flow the intakes. At wide open it ran really good, part throttle was terrible. Pulling hills it would buck and shack so bad you had to let off. It took a year of messing with the engine to figure out the exhaust was pulling all the fuel out when the valves overlapped creating a hugh lean condition. It took a exhaust temp gauge to find the problem. When it acted up, the exhaust temp would spike, then settle right back down when I let off.
Joe
