Dove it twice over 10 years ago, used "H" valved singles (LP 125s). Not real deep, made the second restriction which we decided was far enough. Will mention that the canister had to come off, we dropped a stage at the restriction to have full tanks on entry, and it was a tight fit.....and you know I’m no jockey. ;-)
I’d do the cavern if have a weekend available, did it in Nov of 12, it’s worthwhile by itself, but my current choice of configuration won’t fit through.