This engine is sideways in its car of origin. Funny...it's STILL sideways...
If you look at the picture of Potter, hid left knee is operating and simple clutch and there was no gearbox as sutch. I heard it described as a dog clutch - in reality there was no clutch 'per se' - just on or off and thats how he drove it using the stand around the back wheel on the start line (staging?) to engage drive, build up the rpm then rock it forward so it came off the stand and then kiss your arse good bye.
He has deleted the standard belt tensioners and has changed the belt layout to a single belt. Underneath all that it looks like 308 head and block castings.