Early Honda engines rotate the wrong way so they can't easily be used. Aside from that you can use just about anything. Track/Kick 1.6 must be the easiest. Have a look around the boards you will see what others have used. I personally have seen more differerent engines fitted than I can remember, Ford Crossflow, all sizes, Ford Pinto, Ford diesel, Nissan 1.5 pertrol and diesel, Vauxhall SOHC, Peugeot and VW diesel and TD. Mazda TD (That was a Factory fitment). Then are the 2ltr Suzuki swaps and the US V6s too. If you don't want to modify the shell then a small body lift works too