Just think of making the port window bigger. If you can make the window bigger it should flow more.
I would not make the sides of the port bigger, I would grind down the bosses, if you are going to keep the bosses & not go w/lump ports.
Nothing here was ever posted on what Tom did to his 250-292 dyno heads.
Who knows how much material was removed from the bosses? What were his final dimensions of the intake ports?
Like I said before, you cannot think of his dyno results are the final say so on every configuration on how our inline 6's react with different techniques of porting, different valve jobs, throat angles, camshafts, carbs, intake mainfolds, etc etc & so-on.
They just give you of his results. Good basic results.
Other people have had different results than his dyno tests, and other dyno tests will different results also.
Dyno results will also give you different result when the engine is put into a vehicle. Could be better than expected, could be worse. Point is, you just do not know until the engine is put into a moving working chassis.
What works on a dyno does not absolutely mean it will work in a chassis the same way.
Don't take it the wrong way, dynos are a great tool for tuning,, a chassis dyno is even a better way to tune for real world street & race tuning IMO.
They all have a place to get good feedback on how different combos work & what will not possibly work.
A great flowing head can be an absolute dog of an engine for driven daily driver. This great flowing head on a flow bench can look great on an engine dyno, but it could be a pig when actually installed into a car/truck or?
