I plan on mating them with Leupold Standard scope rings, any idea on the height for a 40mm objective? Will medium do the trick?
Can't comment on your choice of scopes. But Leupold rings are an excellent choice. And Medium high are more than sufficient on a 40mm dia. front objective. Probable leave you with a 1/4 of an inch of free area under your scopes front objective.
At times because I wear glasses w/bifocals I wish I had High rings under my scope. Especially when targeting my rifle for long distances at the range. Would be a convenience for me no doubt. But may not apply to you OP.
By the way welcome to the form Sir.