Dear Muleskinner,
You asked about the Lyman 66WB for the Model 1895 Winchester. In the September, 2001 issue of Handloader, there is a very interesting article by Dave Scovill on conversions of the Model 1895 (USRAC-Miroku) .30-06 to .375 Hawk-Scovill and to .411 Hawk (which are newly developed cartridges somewhat similar to the older .375 Whelen and .400 Whelen, without, it seems, the headspace issues of the latter). The conversions were done by Fred Zeglin of Z-Hat, who is, I think, also located in Wyoming. The photos accompanying the article show the .375 wearing a Lyman 66 sight. I cannot tell which of the 66 variations is used, but it is clearly a 66, and that would lend credence to what you were told by the Brownell's representative. To be able to use a 66, which is readily available, would be a nice convenience.
The truly correct Model 1895 receiver sights, from an historical perspective, are, as I wrote before, the Lyman 21's and 38's with their very distinctive long, left-side arms. For practical, present-day use, however, the Lyman 66WB may be an excellent, available alternative. The reference marks on the 66 would be quite convenient if you were planning to experiment with different bullet weights in your loads.
Good luck!