Don't give up just yet, a little heat on the pistons and cylinders wouldn't hurt, but stick with a heat gun.
I'm having my best luck with PB Blaster and Liquid Wrench even a little carb cleaner.
Mix them all together and they seem to generate heat.
Seems to be a little hotter and thinner that your normal oil. Must be carcinogenic. Sounds like we need more of a solvent than a lube.
Got my cylinders off today, both bores look doable. Pistons had sticky rings (there are just 4 not 5?) but the LW mix freed them up.
Grudgeon pins are a bit of a problem now. Even with a heat gun I can only slide them back and forth to the outside of the circlip groove on either side.
3 out of 4 clips were missing one eye and it appears someone deformed the pistons while installing them without the proper tool.
I've got some dimensions so I can begin making a removal tool at work tomorrow.
If all goes well I should have the barrels blasted, painted, crosshatched and sized up by the end of the week.
Then on to the heads. Planning on doing a hand lap, polishing the pistons and chambers, checking springs, guides and rockers.
Lots of Liquid Wrench and PB Blaster to remove all remnants of the decades old putrid petrochemical varnish and sludge.
Don in Nipomo