Hope this fills in a few gaps. Here are just a few of the alloy rims available then for high pressures. Constrictor Conloy available in Standard, Asp and Boalloy patterns. Fiamme, Banfi-Canti and Alumlite K.P. The Constrictor Conloy's Asp were the lightest at 15oz. followed by the Banfi at 15.5oz. If you wanted something really lightweight then you went for tubulars and the Fiamme sprint rim was a mere 9.5oz. These would have normally been built with 15/17 DB spokes.
Best wishes and be lucky. Michael Butler Huntingdon UK.