Thanks for your thoughts Ramon and also correcting my spelling
I'd not looked that closely at the bearing support but having done so would tend to agree. Options would be to make something more substantial in metal with about a 2" long bottom or to sit the existing bearing block onto a solid "foundation" but I think I would go for the former and match the support for the main frame of the engine to the outrigger one.
As for your flywheel Fizzy I wonder if one could be rolled from say 50 x 6 black bar, you would be upto the welding job. Once built up into the rest of the flywheel a light skim of the outer face and edges should clean it up OK. The traction engine guys often roll two pieces about 3/4 of a circle each and then cut to give to matching halves which does away with the bits at the ends of the bar that does not roll to the same radius. If you wanted to add a bit more interest the flywheel could be made to look like a two piece one with some dummy joint flanges.
Being quite wide but thin section you could possibly modify a shepherds/hen hut wheel casting, some 12" ones on e-bay.