What are key tips for rebuilding a 5.3L LC9 engine?

You can never be too clean! A grain of sand can lead to a bearing failure!

If you’re gonna rebuild that, how are you going to do a valve job on the cylinder heads how are you going to bore out the cylinder block put oversize pistons in and set your ring gaps and make sure they’re installed correctly.

Have the crankshaft cut and use oversize bearings without having any of that equipment.

Go with the ARP headbolts. Only have to torque them. I have talked to some that has done this..Instead of using the factory ones.

If you don’t know. Pay someone who does.

Def clean all head bolts with brake cleaner and blow them out with air very good. Use good torque wrench. Replace oil pump pickup tube o ring.

Also replace whole rear cover imo and use alignment tool to guarantee it is right.

Super cheap on Amazon.

Take your time, grease cam very good and inspect cam bearings etc.

Ask questions if you don’t know!

As Grant said above, cleanliness. Closed, clean garage. Cleanliness also includes oil from your skin. Wear latex gloves when handling finished journals and bearings.

The tools you’ll need aren’t terribly expensive. You’ll want to have the ability to inspect things. Telescoping gauges and OD micrometers for bores, OD micrometers for journals are an economical solution (although even calipers/telescoping gauges are OK for bores).

Valve spring compressors, ring compressors, a way to prime oil, stuff like that.

You can get all kinds of information on here, and most of it is spot on. But with out proper tools and training, you should not assume you can do this unless you have extra money to waste on mistakes or hindsight. A long block would be a good idea. Boring, valve jobs, crankshaft work will have to be done at a machine shop.