I have an .22 rimfire 1885 Winchester/Miroku that I want to mount a Lyman Jr. on for .22 bpcr and need guidance on how I go about determining what block height(s) I need. Specifically, what height blocks do I need (how do I figure out what height is required .e.g. 3/16,1/4" etc.), are both blocks the same height?  The rifle had been previously drilled and tapped at 7.2". Your help would be greatly appreciated. Thanks, Tom

I did the exact same thing on my Miroku/Winchester LW .22, by employing the lowest blocks I had (3/16") and they work swell. I wanted low as possible because of the low comb height exacerbating a good cheek weld with highly mounted scopes. 

Assuming the rifle's barrel is half-octagon and thus the same diameter over the length of the scope mounting field there's no need for differing height blocks. Unless of course you're seeking 200 yard+ capability then you may well need to have a taller rear block. 

On said .22 I like having dual scope capability. Sometimes it wears a Lyman Jr. Targetspot and sometimes a "modern" Sightron Rimfire scope (which is on it at the moment). Have screwdriver will travel!

Thanks to everyone for your suggestions. Tom