A Ca 1913 LAC catalog describes the H bbls as "Best London Twist". I have one H grade 12ga with a total weight of 6½ lbs & is built on a regular frame, not the XX one so they definately would not be described as "Heavy" twist.
There have been a "Few" Ds guns surface which have the H appearance, some listed in the LACA SN list. Seems the basic difference in these is the total lack of engraving, no forend eschution or metal tip, & possibly a lower grade of wood & checkering pattern.
The parts gun is an early G, note the plate mounted sears & also the pin through the frame bar, just where the contour starts. This would tend to indicate a two hook cocker. If one need many parts for a gun of this vintage suspect would be rather hard to come by as this version was rather short lived in the ongoing development of the Lefever Gun. Would seem that 65-70% of Lefevers are in the later Large Single Hook version with the remainder being divided between side cockers, rod cockers, two hook cockers & the small single hook cocker.
The price does seem a litle steep, but if I had it I wouldn't let it go for $50.00 either. I would highly suspect I could get that for that push button forend alone.


Miller/TN
I Didn't Say Everything I Said, Yogi Berra