Will my centrifugal clutch fit?

I've have centrifugal clutch questions. I bought a kit from gasbike.net to convert my 48cc grubee to centrifugal clutch and I don't think it fits, but is so close. The pull start went on OK and works, but as you see in the photo is slightly big, and doesn't match the gasket. The clutch side matches good but there is about an 1/8" gap between the case and cover. The original clutch is too thick and as you see in one photo the center screws will rub on it. Is there a way to make the clutch pack thinner? Aslo what is the big bolt in the side cover? All I can think is to lock the clutch so that the big crank bolt can be tightened. Also there is an extra big bolt with the kit that looks like the big crank bolt, but has a long pin coming out of it. Any idea? The kit came with zero instructions.

Thanks

Rod S

I have a great selection of tools but no machine shop. I could probably be able to get a piece of 1/4" aluminum and grind it out to make a thick gasket, but I wonder if the gears and all would mesh OK. I'm thinking I will just hold onto this and just try it on a future 66cc engine. Do you think it would fit on a 66/80 engine?

thx
Rod S