Hi Steve,
If you allowed for the overhang when fitting the arm then I can see how it would work
I know all about limited space in headshells with the M3D because it's such a bloody big bugger!
My FR S/5 is not exactly small as headshells go, but in order to accommodate the M3D so that it was correctly aligned, I had to create more space by cutting the (chunky) cartridge wires I use to half of their original length, solder the ends directly to the headshell pins, and SQUEEZE the cartridge towards the back of the headshell, near enough as far as it would go, to obtain correct alignment.
It's one of the reasons why when recommending the M3D to people I always state that a much bigger than average headshell is needed to accommodate it, and then only if it's of the right mass.
Out of interest, how would you compare the sound of the M3D to this vintage Dynavector of which you speak? Which model is it? If it's good, I may have to add one to my collection!
Marco.