Idea
allow cardtype change even wo delete permission on old+status
allow cardtype change even wo delete permission on old+priority
allow cardtype change even wo delete permission on old+tag
allow cardtype change even wo delete permission on old+issues
Internally, Wagn deletes a card when you change its cardtype, so you can't change a card's cardtype if you don't have permission to delete it. You should be able to.
above is not correct. card is not deleted; wagn just explicitly checks that permission.
allow cardtype change even wo delete permission on old+discussed in support tickets
allow cardtype change even wo delete permission on old+relevant user stories