Engine Assembly

Clean clean clean - even if you had the machine shop clean the block. Wipe the bores in the direction of the hone with a white paper towel and laquer thinner or brake cleaner until the towels coem out clean as they went in.
Visually inspect every oil passage and if possible - use a cleaning brush to go through them prior to install.
I second the oil pump disassembling- but Idon;t pack with grease. A simple coating of the rotors is enough and won;t clog up the passages or get stuck in small orifaces like lifters.
I use either assembly lube, or a mix of straight 30 oil and white lube for the bearing surfaces and pivot points.
Don't forget under bolt heads when you're lubricating main and head bolts and rod nuts.
Tap all threaded holes prior to final block cleaning.
Torque in at least 3 steps.
Make sure the block, crank, and rods are all at 60°, prefrrably 70 if you are using tools to measure for the cearances. If you cant get them warm - make sure the tools are just as cold as the parts...
Make sure if you are filing the ring gaps that you don't leave sharp edges at the bore side or the sides of the rings at the gap.
Make sure you take a moment to polish the sharp corners of the pistons - the valve reliefs and the edge of any dish to round the corner off.
Number all the pistons and rods before you start assembling and verify the pistons are going in properly.