It's made it with hand tools and a router, no real measurements as I made it as I went along. I started with a slab of 3/4" thick 6061 aluminum and cut a piece to match the dimensions of the back of the receiver. Then I made a jig to hold the piece while I used a plunge router to machine out the inside and the backside that locks into the receiver. After drilling the hole for the stock bolt I made another jig to run the part through a thickness sander to taper it to give the stock the right angle. The buttstock as I said was a surplus takeoff from Canadian Tire that I cut and reshaped to fit the adapter. I didn't strip all the original finish off, instead I mixed up some stain to blend in the color where I reshaped it and use Waterlox finish which gives it the deep rich tone like shellac in cosmoline for 60 years and retain the original stamping marks. To attach it all I was unable to locate an M12x1.0 bolt long enough so I used a steel brake line fitting with M12x1.0 threads and was able to tap the inside to accept an M8x1.25 160mm long bolt I had. In the photo is an aluminum brake line fitting with an M6 bolt and the adapter is now about half the thickness and painted black.
Because of the profile of the stock you have to get up on it to avoid "AK cheek slap". Nose to receiver helps avoid the feeling of getting hit in the cheekbone with a hammer. It's like high heels to a woman, they look cool but hurt. Maybe I'll name this thing "The Stiletto"