Hmm. If it got 3.5" wider and 4.7" taller, then I'm not sure I'd say the width grew more than the height.
But I presume it's the centre of gravity that matters, so probably the clearance that matters more than the ROPs height. The B01 is 325mm clearance, the B50 is 370mm clearance, for an increase of 14%. The B01 is 1245 wide, the B50 is 1365 wide, for an increase of 10%. Unless the engine is mounted a lot higher in the B50 than the B01, I'd say the centre of gravity is probably also ~10-15% higher, I'd call that basically the same stability, and as you say spacers would make a bigger difference than these measures would.