Nothing against Mark/Marcie, but I like Shortino much better and at least he is still making a respectable living in the business today unlike Free.
Paul has ably filled in for a lot of guys. Of course his biggest role was filling in with Quiet Riot, but he also filled in good with the band Heaven and Earth and should fill in good for King Kobra.
He isn't a flashy or spectacular vocalist but he is a good, solid, professional veteran journeyman singer who will never let a band down in the studio or on the road.