Welcome to the group dude.
The cheap eBay exhaust systems will only rust, and the welds will be poor quality so will end up cracking & splitting, causing major blows. As they say.. buy cheap, buy twice.
If there is no history of the inlet valves being done then get it done, as it will be bad purely due to the age.
Again the same with the cam follower and diverter valve. There has been many revisions on the diverter valves as well, the latest being 'G'. If there is no history of it being done, then for the sake of how much both cost I would get it done purely for peace of mind.