Since all 20, 21, and 22Rs are interference motors, your valves are most likely bent. How fast was it spinning when the chain went south? The slower, the better your chances are for less damage.

To check for bent valves, turn the crankshaft until the timing mark is at 3 or 9 o'clock (this will position the crank away from top dead center). Next rotate the camshaft and check for excessive valve to rocker arm clearance. This will immediately show the bent valves.

What year is your 22R? There are two families.

1. 75' to 84'   20, 21, and 22R's
    98 row timing chain  thick head, and tall block.
2. 85' to 95'  22R's
    96 row timing chain  thin head, and shorter block height.

A 20R head will therfore only fit an early 98 row motor without added modifications.
Putting the 20R head on a matching 22R motor will raise the compression from 8.7 to 9.7 to one.
I have done many of these conversions with great results.