I have some as well, my hands are toast now, had eyes dome 15 or so years ago.
Lots of good info here .
I started out recutting checkering on old shotguns mainly, as I seem to have lots kicking around.
Than work on little 22 rifles.
I found about one hour is all I wanted to do at a sitting.
Lighting is key, I always used a low light to check when near done as that really shows up any poor , high, etc points.
I always found ends at boarders where it went to hell, but also, if you are doing a new stock, don't cut all the borders first, that is one way I found to keep it neat.
I think I have about 6 or 7 handles, I use 20lpi , but lots of recutting seems to be 16 or 18 in US. Likely have 2 or 3 dozen ,new and used cutters
I have touched up cutters with fine diamond or saw files. Should have a little booklet somewhere, that I got when I started.
I have done 32 one time, but that was on pistol grips for myself, so did not matter about the many hours invested.
It is temping to go back and recut a line or two when 1/2 way done, not a good thing as then you end up having to redo the whole panel, finish, than touch up if required.
Trade EX has/ had one English cutter listed, I got one, when I was buying some stuff from Anthony one time. price was right.
Btw old tooth brushes are great to keep the lines clean when working, and when oil finish to clean out oils as you don't want it pooling when finishing the lines with what ever finish you use.