You know even if he wasn't available why wouldn't they still have used the ghost of Paul Stoddard anyway. They had Jeremiah's ghost even though Anthony George didn't play him.
I would've like to have seen the goodbye scene between Barnabas and Vicki with AM back as Vicki.
But Paul's face was unharmed and perfectly recognizable when he died, so the bandage ploy was out (and they couldn't very well use a wedding veil with him (he said completely facetiously ).
Well, I guessing that they probably figured they could get away with having another actor play Jeremiah's ghost because, when Jeremiah died, his face was all bandaged and that's the way they had his ghost appear as well (and with Josette they could sometimes get away with not using KLS because Josette often appeared with her wedding veil over her face). But Paul's face was unharmed and perfectly recognizable when he died, so the bandage ploy was out (and they couldn't very well use a wedding veil with him ), and they probably didn't want to recast because, well, they'd had sooooooo much luck with recasts (he said completely facetiously ).
I don't think Barnabas shot Jeremiah in the face, so having his face wrapped up seemed rather weird. They could have had Paul's ghost be a swirling light, sort of ectoplasm type of spirit,, or in the shadow so you wouldn't be able to see his face.