For a custom .350 Rigby I would have nothing but the Mauser shroud-safety...I swallowed the hype of M70s safeties
on custom mausers and spent big on some Joe Zoofall/Jasper Rayburn units and I look back and wonder why.
They are by far the best made 3 pos. safety you could ever find for M98- machining, fit, finish was impeccable.
but to put something from an M70 on a .350 Rigby magnum Mauser is bastardisation in my mind.

Harry Selby some decades ago(80's) had D'Arcy Echols fit a 3pos. Zoofall/Rayburn to his .416 Rigby Mauser,
and it was subsequently removed and the original Mauser clunker refitted.

Images you see of Harrys .416 typically display the mauser shroud, but here is a rare photo with 3 pos. safety:
( note also the aftermarket trigger shoe) the rear charge slot hump has also been removed, I believe by the Paul Roberts
shop as part of the rifles original build process, but you can find other variants of Paul Roberts built stdM98 .416 rifles that
retained the rear bridge charge hump.

Non factual assertion removed.