An AMG Blog follower from Germany reminded me of the Daniel Hohrath books. Albeit we are looking in most cases at mitres dated 1786, we will have to assume the same die was used.
The heights of both grenadier and fusilier slightly between regiments:
Grenadiers 23.5 up to 26 cm. IR 15 having 28.1 cm
Fusiliers 23 up to 25cm being the norm. The 47th fusiliers was an original mitre dated 1743-1786 and this is 23.5cm.
So we can accept that the variance in height between grenadier and fusiliers would be hardly noticeable.
I made the mitres on my fusiliers fractionally smaller, not sure I was right, but if your fusiliers are marching around in very small mitres, well...........................