If the purpose of the rebuild is to bring the engine back (or close as feasibly possible) to it's original performance, what are some things that should always be replaced?

This obviously depends on the condition of the engine, so let's say a 300,000 km engine which had regular oil changes it's whole life.

Gaskets, seals, belts, bolts, etc. yes you should replace, but how about components such as valves, valve springs / hydraulics, piston heads, connecting rods, camshafts, piston rings to name a few?

If the purpose of the rebuild is to bring the engine back (or as close as feasibly possible) to its original performance, what are some things that should always be replaced?

This obviously depends on the condition of the engine, so let's say a 300,000 km engine which has had regular oil changes its whole life.

Gaskets, seals, belts, bolts, etc. yes you should replace, but how about components such as valves, valve springs / hydraulics, piston heads, connecting rods, camshafts, piston rings to name a few?

If the purpose of the rebuild is to bring the engine back (or close as feasbily possible) to it's original performance, what are some things that should always be replaced?

This obviously depends on the condition of the engine, so let's say a 300,000 km engine which had regular oil changes it's whole life.

Gaskets, seals, belts, bolts, etc. yes you should replace, but how about components such as valves, valve springs / hydraulics, piston heads, connecting rods, camshafts, piston rings to name a few?

If the purpose of the rebuild is to bring the engine back (or close as feasibly possible) to it's original performance, what are some things that should always be replaced?

This obviously depends on the condition of the engine, so let's say a 300,000 km engine which had regular oil changes it's whole life.

Gaskets, seals, belts, bolts, etc. yes you should replace, but how about components such as valves, valve springs / hydraulics, piston heads, connecting rods, camshafts, piston rings to name a few?