Very much appreciate the answers.
I've seen the sight calculation chart in the Brownell's catalog. I used Hamilton Bowen's simplified method (sight radius in inches X amount of POI correction needed in inches) / range in inches = amount of correction for front sight in 1/1000" and came up with 0.0471". Added to the existing front sight height of 0.410" and adding a 'fudge factor" to allow some latitude for adjustment to compensate for different ranges and ammo this gave me a figure about identical to what guncrank advised.
From what little dimensional data about the Williams "Shorty" I can find it's supposed to be about 0.250" across the base of the dovetail. Since this is the size guncrank specified that he'd use, I'm guessing that this is the model he's talking about. It's supposed to be made so that it can be installed with silver solder or a screw. The screw requires either d&t'ing one hole or using a "gib lock" adaptor in the dovetail.
I have vanishingly little experience in "silver" soldering and it seemed to me that trying to use the Williams factory adaptor would present the same kind of dimensional problems because it too is sized for a standard 3/8" dovetail. That's pretty much why I thought that grinding-down the existing front sight to match (as much as possible) the approximate barrel contour and using it as the "adaptor" might be more practical.
Jim, I was really, really
tempted by those beautiful NECG banded ramps you mentioned. They look so elegant and have so much of that old British "Best Quality" custom panache! If this were a nice Belgian (or even Miroku) Browning we were talking about, I might be more willing/able to rationalize giving in to that temptation. As it is, I've already dumped way more time and cash on this little venture into "From sow's ear to silk purse" territory than most sane people would even consider, and I greatly fear that the cost for the additonal part(s) and the skilled labor I'd have to buy in order to go that route might make even my most tolerant and indulgent of spouses think seriously about having my mental competance examined
I will be giving the Brownell's tech folks a call to see what they've got to say before I buy any parts, just for some "belt-and-suspenders" reassurance. Hopefully, I'll at least end up with a usable sow's ear.