I have done two jobs with those kind of blocks you describe. Unless you got
what you have for free or close to that one usually purchases the necessary
half blocks with the initial order. I don't recall all that well perhaps
there is a whole block with a double middle you cut or crack. The other
end on my applications just ended up kind of like a stair way. Probably
more rain around here, fill the voids with pea stone, tie back into the
bank by putting a hammer drill hole and steel rod going back into the bank
as needed. Cap the top with a thin layer of small aggregate concrete. Pea
stone and drainage perforated pipe at bottom in the bigger job.
Those blocks weren't cheap, the smaller job where I bought them I got a
discontinued color/texture and I bet a pick up loaded would have been about
$500. Personally I think you should think about water on the diamond blade.