Oh, how have I missed this most magical of threads? 
I will be joining the ranks of hybrid engine rigs soon; my 84-ish 22R tossed a crank bearing and I scored a complete 20R for free and have been thinking about this build for quite a while.
This is the technical info I have been looking for! I don't want to overbore the block (will lose compression, right?), deck the head a bunch (just make it flush again), use the wrong valves or anything else wrong. I have my evil plan posted in my build but basically I'm planning on:
20R head, cleaned up, ported, engnbldr O/S valves ($58/set), find a way to replace that plate at the back of the head since I don't believe in EGR/emissions
22R block, hopefully just honed (slight bore if needed), regrind crank due to bad bearing, double row timing
port intake as described above, 22R carb ('cause I already got one), new oil/water pumps and steel timing guides, engnbldr master rebuild kit and his 261 crawler cam 'cause that's what seems to be working for people.
If anything is screwy, please let me know... I am totally open to suggestions etc.
>>Dan
Remember that over boring will actually raise compression, because you are increasing the relation of the bore size to the compression chamber, which is staying the same. Just bore as much is needed to make a round hole. Decking the head/block should be minimal so you don't have problems with the timing chain length. Make sure you know about the early/late blocks (-84+) which have different deck heights. Someone else can chime in about this, as I am just getting into the early engines now that I have an '83 and am green on details.
I run the 261c in a 22RE and it's nice, but I would definitely go bigger cam in a carb'd 22R. LCE and Comp make some nice grinds. Good luck, I hope we didn't hijack this thread too bad.
