Single Throttlebody Sizing

[Richie-Van-GTi 71 2 Cars]

Im currently building a bike engine single seater project. I am using a Vtwin 600cc engine and converting it to fuel injection from carbs. Previously had 2 mikuni 32mm carbs, one on each piston. Going on various website calculators they recommend a throttlebody size based on race use of around 33mm but that does not say if its on each cylinder or across both. I suspect across both. Can anyone confirm this sounds about right? Also any idea who makes bespoke billet bodies or stocks a wide range of sizes?