Very nice indeed.
I wouldn't worry too much about how you cut the dovetail, as long as they work, why worry.
There is too much emphasis placed on getting things perfect and using the correct tools, but there are many ways to skin a cat. It's the finished article that counts. You wouldn't believe the things I get up to if I don't have the right tool to hand.
You can, if you are only using thin tooling, say 1/4" square, make the blocks with a narrow slot to take the thin tooling but make them only half the height. As long as the piston face is pushing on the back, then they are fine.
I have about a dozen of these half height ones to make, to take tiny tools that I have ground up, and by making them as I suggested, I will saving myself loadsa cash on material costs.
John