While none of the Lemmings Plus series have official SuperLemmini conversions, and indeed most of them would not be suitable for it (due to use of new objects / skills / styles), if you're after this purely for the sake of testing vertical scrolling in the engine, converting the Lemmings Plus Alpha levels might work well as they do mostly use the classic styles and there's a few vertical scrollers in there. There are 5 levels that use the SMS Sega style, but none of them are vertical scrollers anyway.