The throttle set ups are seriously difficult to fathom! If you look in chapter 30 in the FSM you can see loads of variations on the same theme.
I reckon that you'll probably need a pre-1980 set up for an M pump.
Greazzer if you get really stuck feel free to get in touch with me - I can probably source what you want over here but be warned Holland ain't cheap and neither is the postage...
...I reckon you'll be better off trying to find out if the parts on an "American" 300CD are suitable for your needs. From about 1980 onwards here in Europe it seems to me that we all got the M/RSF pump which is slightly different. Pictures of the older European M pump and the M/RSF pump are here (if this helps)
http://www.peachparts.com/shopforum/diesel-discussion/306090-papas-got-brand-new-om617-ip-play.html