Thanks to both Lozza and Mark for your time and replies. I have absolutely ZERO knowledge of Maico's, barring of course, being able to remember when guys with distinctly thinner than average wallets used to be able to afford them!
From your answers and the little bit of info that I already have, it looks like the 250 and big bores were different in length and width. So, the 250 is 132mm x 17mm wide, and the larger bikes (Im going to assume that the 490 is a bored 440??!!), 136mm long x 16.5 wide.
The only reason Im looking into this is as a possible solution to the large number of otherwise uneconomic to repair Alpha/Greeves cranks that I have, the Maico 440 rod (16.5mm wide x 25mm crankpin x 22:18 small end) and Suzuki RM/PE/TS piston route being a viable solution for one or more of them......
Thanks