Isn't there an adapter that can be used to use 2-bolt cleats on 2-bolt shoes? I seem to recall that it is a plate with the drillings for both patterns. Bolt it to the shoe and the cleat to it. (But it does add stack height. How much I do not know. I've never seen them. I have heard their were well made and worked well, if you could live with the stack. The name? No clue. Sorry.)

For some of us there is a huge difference between SPD cleats and SPD-SL (and all the LOOK systems and a few others) and that is the inability to lock out float. Float would have had me on knee replacements decades ago.

Lake used to make their less expensive shoes with the bolt patterns for both. (In those days I was cash strapped and the expensive ones were out of the question so I never looked.) Now it seems it is either/or. I have two pairs of their best of two years ago, 3-bolt, really nice leather, dual BOA and as comfortable, at least on my feet, as shoes can get. (Nice big toe box!) These shoes cost between the OP's wife's sale and retail, so not cheap but if my experience with LAKE hold true, they should hold up and be joys to wear most of the rest of my life. (Oh, the burgundy red goes wonderfully with my freshly painted Mooney and Hermes Red Saphir shoe polish 1) make that leather come alive and 2) is color perfect!)