For engine internals, one can take an educated guess.
3.0 litres v10 - each piston is 300ml - with an average sized crown, say on an oversquare engine for max flow, I'd imagine it'd be 70-80mm?
The RB25/26 is 86mm.
The stroke would be 50mm?
Actually by my very crap back of serviette calcs, an 86mm bore with a 50mm stroke would make the a V10 of around 3.0 litres.
Given that the RB26 runs ~73mm stroke, I'd imagine a 50mm stroke or less would make for twice the RPM given sufficient materials and balancing.
T.