Would the oil pump and ported heads fix the whole oil starvation problems?
If you have oil starvation issues, the only way to sort that at a minimum is to sump off. Clean pick up. Front off to do oil pump. Do chains while you’re at it because they all have to come off to get to the oil pump.
If you have an issue, the cars service history will be questionable. These cars need oil changes every 7500 now they are older. Holdens 15000 was not adequate long term, but was for the new car warranty period. Oil changes out of warranty were probably 20-30k on many cars. Then the insides are gunged up. PCV was too small and things got worse. Oil leaks start as crank case pressure couldn’t exit.
(There is a fix for that in the HowTo section.) gunked up motor then has blockages around the tensioners causing failing chains.
The problem with these motors are the owners. Not the engines.
A rebuild would be expected to sort a gunked up engine properly. Or start doing oil changes with 5W40 diesel oil. Every 5000-7500. Filter changes every 2500.