All MR bows are yew. Some people say there were some whitewood bows on MR but I reckon due to quality of the research that would be long known and published in scientifical journall for peer rewiev.
If you make whitewood bow to MR dimensions, couple of things happens.
a) Density of your wood is not very high. The bow will bend and be spongy, wont shoot well and eventually break
b) You have high density stave,that if made to MR dimensions (yew dimensions) it is completelly nonbendable.
We harvest "nuclear ash". It goes with SG 0.85 and higher. To get reasonable weights (100-110#) you only need it 30-32 mm wide at girth and the taper is reasonably lankier with very narrow tips. 35 mm width gives you 140#.
Since I cannot accept tudor bowmakers as idiots and I assume they understood wood, I reckon that any original whitewood english bow will be recognised immediatelly by having different shape and taper than yew one. That same goes for laburnum bow. This is overlooked wood, but it gets listed by severall original sources as wood for courtly and flashy bow. I reckon that laburnum bow will have slightly different shape and taper and will be lankier than similar weight yew.
Jaro