I didn't mean to scare you away from buying the adjustable ring compressor by saying the process needs a bit of confidence when you ram the piston in. If the rings are not on the piston yet, buy a $8 ring expander.
I did approximately 30 engines in my life, means I am a novice everytime I build one, and it works 80% of the time for each piston immediately. The other 20% get a second turn.
Most important is the speed at which the piston gets inserted and that you have the tool ring square on the block. I feel that just pushing the piston down with one hand won't work. I use a hammer handle to knock it lightly.
There are endless debates about how to position the ring gap, but I leave that for another time!
I agree with Kirkham about the
oil cooler. My mate rebuilds engines and automatic transmissions. The
oil cooler gets replaced.
The bearings need to sit dry in the block or rod to transfer heat. You may find them oily, however, when you strip an engine...
Of course,
oil the operating surface. Also a drop on the front and rear main seal will avoid it burning away during break in.
PS: A bit of history. I lost a cam lobe in an all aluminium Chevy (Reynolds block). I had water seepage around the head studs leading to reduced lubrication. I lost a complete side-oiler because the builder used 390 rods. Apparently tested, but the beach marks at the crack speak another language. I am now extra careful. Buy that oil cooler..