If your car has done over 100,000 of mixed work, alot of the air sus stuff will be on its way out.looking back over the years of caring for Classics and then P38's saw plenty of failed cars towed in. Perished air bags,failed height sensors and worn out compressors in the main.
If I was daft enough to buy a P38 and use it as a daily driver I'd do the lot - unless it was obvious they were fresh or had recipits etc.It all wears out,all makes for a bumpy ride on the stops.Planned long term maintenance is something most customers dont want to think about.(Pay for) But, if you want reliability,and you KNOW all these bits wear out/fail - then you can decide for yourself.