The modded engine is gone now but being from the same bloke who done the MG66 & Godzilla I reckon it would be a good product. I wouldn't mind getting another GO Engine as I have the pipe already, not in a rush though as the Godzilla is still going alright, could get a pinch done if needed as well, its a good engine.
The MG66 might be the way to go next, or get in touch with the engine builder.