Anything that I should use caution with when rebui

Unless there's been some sort of obvious previous problem, you don't need to worry about sleeve-stand-out above the block-deck. Same goes for the old "X" or "O" marks on the sleeves - I assume your new sleeves have no such marks? Piston pins are a push-in fit by hand. Sometimes carbon on old pistons holds them in a bit, and also - you often will ease things by taking a low-heat torch and warming the aluminum pistons - they expand fast. If pins are loose in the old rod holes - then you need to install new rod bushings and have them honed to fit the new pins. In any good diesel rebuild - all the rods should be checked for roundness at the bottoms - where the bearing-halves are held. Diesel rods tend to get egg-shaped over time. It's simple machine-shop process to "resize" them. Once the block is clean - the new sleeves should easily push in by hand, or fall in - before the new seals are put in. If not, clean it up. Then, you can use any kind of non-oil based lube on the new seals - and then push the sleeves in by hand. Dish washing detergent or handsoap works fine. But - if any oil touches the one orange seal - it will swell up like a balloon. It's designed to do that AFTER the engine is assembled - but obviously not WHILE you are assembling. In regard to the rear-main seal - I wouldn't mess with it if it's not leaking. And, there are several versions depending on the vintage of the engine. The first seals can be very problematic to fix - and use a seal that rotates with the crankshaft and rides against the rear cast-iron housing. The second type is simply a one-piece conventional lip-type oil seal that is stationary. Even if you have a slight leak, putting in new main bearings might correct it. And - break-in? Main thing is not to run constant speed for long, and not to let it idle. Until the new rings establish a slight wear pattern - then can "walk" around the pistons and then all the gaps line up - which causes problems. Just start it - run a bit a a moderates speed and make sure oil-pressure is okay. Then - since you don't have a dyno - take it for a ride in higher gears - high enough so then you hit the throttle it has to work pretty hard. To that, off and on at different speeds and you'll establish a good wear pattern fast. Just don't lug it. If you are doing any valve work in the head - make sure the installed valve head depth below head mounting surface is correct. If you grind the valves and seats, and get the valve-heads too deep, it will be a poor cold-weather starter. Good rule of thumb is .025" depth for the intakes and .040" depth for the exhausts.