I think putting it up with a 325 cfm carb and a header would be a typical 20r. The reason I'm interested in this is that my 20r has clearly different and more eager driving characteristics than my 22r. That head is really doing something despite the smaller 2.2 displacement, even bone stock.
I know it's probably not possible to account for the better flow of the head but it would be fun to see what the smaller cubes and square bore/stroke relationship do to the numbers.
the 20R head and intake are greatly superior to the 22r as far as flow. BUT the stock round 20r carb is a 190 cfm carb, lce makes an adapter to put a 22R carb on the 20r intake. I got the weber years ago and that made a significant improvement.
I ran a 20r head on my 22R block for a couple years before I blew it
![Sad :(](https://board.marlincrawler.com/Smileys/marlin/sad.gif)
but I will build another one.