hvacr,
cant help you much with the sleeve deal. someone here can i am sure. that big nut is very tight and a normal nut (ccw) to loosen. with the pan off you can chock the crank against the block with a piece of wood and get some leverage,this worked for me, but scared the doodoo out of me, i was kinda worried about breaking the side of the block. or if still in the car use a large breaker bar and use the bump the starter trick. Are you doing this in the car? the crank would lift out of the block once the the main caps unbolted and removed. not sure this can be done in the car with the flywheel still in place.
Here is a useful thread here about the sleeves.
https://www.britishcarforum.com/ubbthread...true#Post111068
when i did mine i dont believe there were any sleeves in mine...
if your on a budget (and who isnt) you could ridge ream the tops and install some new pistons and con rod bearings, get you head redone and try it from there. I would definitely replace the thrust washer on the crank, for they are a known weak point in these engines, with that many miles. also the timing chain and tensioner.
it cost me about 1500$ to rebuild mine. that includes the price of a new crank and NO machine work (someone had already done it for me) a new cam set(came with springs and tappets), chain and gears, bearings and water and oil pump, gaskets and misc.
I would believe that you should be able to get this done in a couple of weeks of spare time, once you have the parts you plan to replace.
and if you need a hand with anything Randolph is just a sweet tour up the road from me.
mark