Good sources of dual pivot long drop nutted brakes

A common problem for reuse of older steel 27" bikes with 700C wheels is that we need long drop calipers. it is hard to get a drill in to drill the front facing side of rear bridges for Allen key brakes (like those from Tektro) and drilling out the rear of the fork hole is always a bit sloppy eventually. So we need nutted brakes to avoid the drilling. And in order to get good braking, dual pivot is better. I have found brakes with all 3 attributes a few times (old Shimano Nexus fronts from the US and some sort of no name brand rears from the UK) but is there a place to get them from at a good price in Australia? I have paid just under $30 including postage for each caliper each time - is it possible to do better?

Tektro listened to the people that were converting their allen bolt R556s:

55-73mm reach, nutted mount, USD$72/pr:

Not possible to beat the quality and price by buying in Australia to my knowledge.

FWIW I was looking at some long-drop Miche calipers on evil-bay a few days ago, from memory about $50 the pair posted from UK.

Edit - disregard, just looked 'em up they’re not nutted (note to self about reading stuff) and only 57mm drop

many thanks guys. I bought one R556 pair with Allen head bolts a couple of years back and never mounted the rear one. i have a few projects on the go and this will help me. The Tektro gear is just a little bit better quality than the others I have got by the finish on them - pretty similar otherwise.