The 7402s get my vote for best single pivots, too. I really can't think of anthing to improve on them. Sounds like you had the same idea as Campagnolo with their combination of single-pivot rear & double-pivot front.

For longer reach brakes (49-57 mm), I guess the 6400 series was the last of the higher quality Shimanos made in a single pivot style.

On my bikes with a higher fork & bridge I often use the modern dual-pivot Shimano BR-R600 or else the Tektro copies of those which happen to have an even nicer polished finish, although they do lack the pivot bushing plate with the tiny bearings. But, for half the price and a better shine I can live with those just fine. I'll even give the Tektros extra credit, simply because the painted logo over the anodizing easily removes with acetone.