I run two old triumphs (Val Page 1936 Mk5, 1950 Speed Twin on worn out pre monoblock carbs plus a 1957 Thunderbird with a Sinners Union and they run and start well and tick over like swiss watches and it all about starting and usng the bikes daily
They will run quite well on worn slides as long as one replaces the needle jets now and then.
I had very worn Concentrics on the Rapide. It started to burn a tremendous amount of fuel, so I installed new Premieres on it, problem solved.
Afterward it occured that clapped out slides should lean things out, not make the bike run rich. The poor mileage wasn't due to worn slides, it was due to worn out needle jets.
A few years later I had the same scenario with a Norton twin. That time I just replaced the needle jets and fuel economy went from 35 mpg back to 50-55 where it normally is. And the bike runs fine with quite loose slides.
Glen