nook
+1y
If yours is an 87 carb engine it can still be done but requires some major cutting on the 20r head to get it to the correct size, it gets pretty spendy too.
If you by chance have an earlier 22r, pre 84 tall deck block then its a simple matter to swap out the top half to the 20R head, intake/carb, exhaust manifold, and your there. There are several 20R heads available depending on the build, the early ones had no bolt hole provisions for botling on power steering, some had no place to bolt on the mechanical fuel pump, and the later ones had it all.
The hybrid swap gains you about a half point in compression ratio and on average around a 5 to 7 horsepower increase.
It gives a little torquier feel off idle because of the smaller straighter ports and valves of the 20r but at higher RPM it lays down because it runs out of air, the engine can't breathe as easy.
Dollar for dollar you could probably upgrade cam, carb, and exhaust and gain more than the 20r head swap would net you.
The hybrid I,m building is going with a big valve 20r head, same as the 22R, some minor port work, so with a little more compression, big valves, better port design, it should still be able to breathe on the upper end through the dual carbs.