Joined: Jan 2010
Posts: 9,830
Likes: 1,807
From: Northern California
Bikes: Cheltenham-Pedersen racer, Boulder F/S Paris-Roubaix, Varsity racer, '52 Christophe, '62 Continental, '92 Merckx, '75 Limongi, '76 Presto, '72 Gitane SC, '71 Schwinn SS, etc.
I imagine that silver 28h Open Pro rims are at this point rather "thin on the ground" so to speak.
32h was by far the most common drilling.
28h rims from all brands are not too common (not rare, but a small minority of total production offered by most rim makers).
Any vintage-profile rim will require longer spokes than any Mavic Open rim.