Which intake manifold

yeah ive seen BMW 6 cylinders runnig mikuni bike carbs great top end bit lack lustre in the lower rpm and you have to really make your own jets a carb that spins a small capcity 4 cylinder or 6 cylinder bike engine to a million rpm is not gonna be jetted well for a 225. and you often need a stub manifold to rubber mount them on.

I supect the best all round would be 3 2 inch SUs or similar dash pot controlled constant depression style carbs
easier to do than webers but still mighty expensive unless you know a 1960s or 70s jaguar junk yard

you only tend to find SUs if us brits sold some cars to you when we had a car industry that wasn't on strike for a decade at a time...

Dave