I have never heard of Barrel Droop on an HW 35 The latch is supposed to eliminate that, and mine do. I have an EB and an E both from 1977 and neither have any barrel droop. As far as scope mounts 1 piece with a stop screw in them are the best way to go. On guns like an R1 they are mandatory due to the viciousness of the shot cycle. The R1 is simply an HW 35 scaled up slightly.
I have a Beeman/Williams Aperture Sight on my EB, and the stock Open Sights on my E. I also have a Bug Buster 3x9 Scope that I can mount on the E but I just used the mounts that came with the scope on that one. I use both my Hw 35's for iron Sight Practice Guns, hence the Iron Sights on both.
I had an old Bushnell .22 scope on my EB for several years and how it survived I have no idea but it did and I still have it. I had to install a Beeman Scope Stop for that one as the mount didn't have enough clamping pressure to prevent the scope from shifting on the dovetail.
UTG makes a bunch of different scope mounts and they are cheap, but well made. I have several of them on various guns.
HW35EB with Beeman/William Receiver Sight.
View attachment 335393 R1 with 1-4X Leupold and UTG one piece mount with stop screw. There was an earlier mount with only two screws that wouldn't hold position.
View attachment 335395