@Jaylordofwaargh 58 pattern was my issued kit, the kidney pouches were meant for your sustainment kit, mess tins/ratpacks etc, & socks/footpowder etc, essentially for when the shit hits the fan & you have to leg it, you've got enough in your battle order to survive independently for a few days, but as far as pouches go, the kidney pouches were only ever meant to be accessible when your rigs off.
But unless you're planning on doing 36+hrs milsims or similar, they're totally unsuitable for airsoft skirmish days, same goes for the poncho roll, just annoying when it slaps on your arse when running (we used to clip ours above the kidney pouches, much more stable).
As for the holsters, they were hardly ever issued because very few had access to pistols anyway, literally you signed out a pistol if you were on guardhouse duty etc, & you were handed a belt with holster attached, which went back in to the armoury with the browning at the end of your stag, so it's no wonder hardly any made it on to the surplus market.
But there was a shoulder holster issued too, not leather, same material as your webbing & designed to be worn over your smock, you might get lucky & find one of those ?