If you can't see the reason behind not using metal for those parts, it isn't worth explaining. Oh wait, I already told the reason.

I am not tying to shoot down your project, I am just trying to possibly save you from having some irate customers when the screws may not provide enough clamping force to seal the float bowl or they break the screws when they install the bowl. 

Do you think Quadzilla owners will be able to see a difference in acceleration due to saving a few ounces on a float bowl when they are almost 390 lbs. without a rider?

I have not found a need for the large capacity bowls on alcohol when the whole fuel system is set up correctly for the power the engine is making.