Hi Don Mac,
The gap on your mill rollers will vary with the brand and size of the rollers.
A good figure to start at would be around 0.040" however with a two roller you may get some tearing of the husk.
Speed of rotation may have a bearing also and what some brewers do is put the grain through at a larger gap initially then run it through again at the final setting.
Some also dampen the grain slightly and this helps with keeping the husks in tack.
Of course all the above comments on gap will depend wether your mill is adjustable or not.
The March pump to my knowledge is not available in Adelaide but Grain and Grape will be able to help you.
Do a search on this site under pumps/ March pumps, and for mill info, Mills/ Grain mills. There will be a few hours reading with both these topics