Hi Lou,
here in Oz I am sure that we have similar transport issues as you have, as well as diethyl ether being used by 'crack' factories and attracting a great reluctance to over the counter sales but at the moment if you can show the seller a genuine use for model diesel fuel chemicals then there seems to be no problems as long as you know the right people to talk to.

I haven't seen diesel fuel in hobby stores for years now and most flyers obtain the seperate ingredients through club contacts.

Interestingly the most common excuse not to sell you ether is that it is on the dangerous chemicals list and when I ask the seller to show me where on the list ether is they can not do so as it is not there (at least it wasn't there the last time I looked!)

Just had a look at a picture of the offending engine mate, and it seems to be a bit of a bugger with modifying the rear main transfer port. But all you really need to do is affect the very top of port or its opening in order to restrict and shape the flow - kinda looks to be too much trouble though.

Nice talking to you.