Replacing the cylinder liners takes no special tools and is fairly easy. I did this on my 1985 block. The trick I found is, from the bottom beat on the liner with a thin punch or screwdriver to fold the liner away from the block. Then put a long screwdriver in the crack and hammer it down. The cast-iron liner will crack and fold in, then drop out easily.

Sand the bores good and lube with WD40. Oil or grease would probably work better but I was afraid of that leaving the liner squirrely. I chilled the new liners in the freezer and heated the block in the sun and with a propane grill underneath, but only got it to ~150 F. I beat the new liners in with a sledgehammer acting on a thick steel plate. Many medium hits seemed to work best. I had to beat harder than I was comfortable, but didn't see any cracks. When it seats on the top groove, you can tell from the sound. If I did it again, I would use a bigger grill and heat the block to ~300 F, where I calculate the liner would almost drop in.

You could do all this with the block in the car. However, you still might need a machine shop to mill the tops of the liners flush (protrude ~0.020"), though maybe a file and stone could manage that by hand. The new liners measured much thicker than the old. I don't know if that is to allow for machining or mine were really worn at 330K miles. You might hone the new liners to fit the pistons using a hand drill and stone, but might take a long time if a lot of metal to remove.

I am waiting to get replacement pistons, which seems to be the biggest hangup in rebuilding the engine. Amazing that nobody makes new pistons, given the number of 300D's sold around the world.