You may also have a point with the "FUN", but doesnt it just sound nice! I bet i dont even see 25 mpg on a good run!
A good 'S' or Prep 142 using the original twin sidedraught Solex 40's, on a run (so the cold run period is short compared to the hot) and mostly on open roads, will easily give 30mpg and I'm talking about running at 140kph when the road is clear and using acceleration to overtake other cars. I can verify this as I have done it many times. With my Solex (or Weber) progressive twin venturi downdraught carb. I would get 32mpg under the same conditions. Using a little restraint, but still doing up to 120 kph I would get 35mpg. I proved this to Chris House last year when I said the Murena would give better consumption than a Bagheera, and we went to a club meeting in mine. We brimmed it before and after and it did 35mpg. His Bagheera gave 34mpg on the trip to Classic Le Mans.
Fuel consumption is always down to the way the car is driven too, but things like brakes dragging as the calipers are not really free will make things worse.
Sounds like plenty of work to be had putting cars right! :-)
To get back to the topic of valve adjustment, I have never had to do mine much as the cams have just never worn as a consequence of using full synthetic oil from new, but I have always put the car in 4th gear and pushed it forward to turn the engine. You only have to do it four times to check all the valves so whilst it does mean getting in and out of the boot, it's not really a big deal. You could turn the engine from the boot, by rotating the cam gear but I'm never keen on that.
Roy