2004 Brompton that needs a lot of work – repair or replace?

2004 Brompton (22 years old!) and so far this thing has served me well for London commuting, but it is really in need of a full update and service. It has 6 gear sram/sachs and the long frame.

I've made some improvements over the last year, but wouldn't say it's a pleasure to cycle.

So far I have worked out I need to replace:

1. The terrible shifters and brake levers. These old style ones seem so poorly made and you have to take your hand off the grip to change gear. So will change to the standard integrated brifters on current models.

2. Replacement rear triangle hinge – currently very wobbly and likely original

3. New bottom bracket (and thus new cranks because things have changed for ISO to JIS and it seems these are not sold now)

4. All new cables for gears and brakes (as well as the derailleur spring set once I change to the integrated gear shifter…)

5. Snapped spoke in rear wheel

6. Seat post liner? At least assume from age it needs doing

7. Bag mount block that doesn't seem to hold the bag securely at all

8. Brake callipers (luckily have these from my brother)

9. Worn handlebar folding catch

10. Potentially: Not sure how great the condition of the hub/bearings of the rear wheel really is

This is coming in to £350?+ (without even getting a shop to do the hinge reaming out or replacing the rear wheel). I am sure there will be more things to do once I start taking it apart, there is some pretty bad rust on the rear triangle.

The question is, is it all worth it, or would it make sense to get a newer model? Either lightly used second hand or cycle-to-work scheme?