Mike,
You said you read all the ideas but did not mention which ones you've tried. Though I hate to advocate destroying what might be an original part, one method that is not mentioned in that thread is using a reciprocating saw to cut a groove in the clutch center as far along the length as access allows. If you stop just short of the shaft you should be able to open the slot with a chisel, which will relieve some of the stress holding it on. Maybe you can actually cut through to the shaft without damaging it. Not sure, so I'm not putting out that idea. If you are lucky, you might still be able to connect the puller after the slot is cut. I have to say, i have not actually used this approach with a clutch center, but I've used it on other stuck parts in the past with some success.
Richard L.