I've seen two G Bodied Esprits with the SHO conversion, one S1 or S2 with the Buick (Rover) V8 and have heard of at least one other with the Buick/Rover engine.
15 or so years ago I knew a guy who had an S2 Europa with a rotary transplant. Claimed he was getting around 220hp in his 1500 lb car.
Have owned, enjoyed, appreciated, and now all gone:
1969 Europa S2 Blue
1970 Europa S2 White (my first)
1974 Europa Twin Cam Special Light Blue
1974 Europa Twin Cam Special #4380R Indigo Blue (my absolute favorite).
1984 Turbo Esprit Calypso Red
2005 Elise Starlight Black
2005 Elise Saffron Yellow
2005 Elise Ardent Red (used as development mule for the LETSLA)
2006 Exige Graphite Grey
2007 Exige S Canyon Red (first customer installation for the production LETSLA)