Anything other than a full teardown and overhaul will be a Band-Aid fix. It's impossible to get the pistons out the bottom- - - -they won't clear the crankshaft and the block webbing, and if you did get them out, compressing the rings to get them back into the cylinders would be virtually impossible.

With the amount of rust damage your first few pics showed, I'm guessing you're looking at a $3K overhaul cost, minimum, with cylinder reboring, new pistons, new cam and lifters, and possibly new pushrods and rocker arms plus all the bearings. An in the frame "rebuild" with new rings, rod and main bearings, and gaskets will be around $600.00 but the lifespan of a job like that will be measured in months, not years.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!