Late Toyota v6 mated with an Mr2 gearbox would be a good choice, more chance of those on your side of the pond. With the LS engine youd be very space limited and probably need to supply an engine/box assembly to Hawk or Listerbell, just to make sure it'd go in. I can assure you it would be very tight or wouldnt fit at all, across the engine bay. If you could find an inline transaxle, you'd have a good chance of the LS fitting in the Listerbell in conventional North/south orientation but not so with the Hawk.