I happened to be browsing through Gerjan's invaluable book on screw-mount Pentaxes when I stumbled across a page describing the factory-installable optional focusing screens. There was a split-image screen availible, so it is possible that the companies that offer this conversion are using an actual Pentax screen designed for the Spotmatic. Given how dim the spottie screens are, I think I'd prefer a Beattie or something like that.
DJE
