The Atlas used the featherbed frame, and was built from '62-'68 - somewhere in the neighborhood of 10,000 built
The Atlas Scrambler used the Atlas motor in a Matchless G12-G15 frame with Norton wheels and Roadholder forks. Somewhere in the neighborhood of 2500 were built from late 1963 to early 1968 (with 5 'specials' built in '69). First batch of 300 or so were stamped G15CS/10xxxx 'N'
This same configuration was also sold as the Matchless G15CS, built at the same time, with somewhere in the neighborhood of 1000 built.
Change the tank, seat, fenders and few other bolt-on bits, you've got the G15MkII or AJS 33
Change the seat and other bits again, put on a set of rearsets, and reverse the shifter cam to flip the change lever rearward, you've got the AJS 33CSR, G15CSR, and the Atlas 750SS ('66-'68 for the Atlas 750SS - essentially re-badged AJS). A total of somewhere around 1500 of these other variants were built, with a grand total of about 5000 Atlas motors in G15 frames.
The P11 series was another hybrid, this time using the Matchless G85 chassis. Around 130 G85's were built, using the Matchless G80-500cc high-compression engine. It was pretty successful as a factory bike in '63-'65. When the bike was finally offered for sale to the public in 1966, it was obsolete, so the West coast distributor for Norton-Matchless suggested putting the Atlas motor in this frame, as was done with the G15/N15. The P11 used AMC forks and wheels. Both the N15/G15 series and P11 series used AMC transmissions rather than the Norton boxes.
About 2500 P11s were built between March, 1967 and October, 1968, with 700 sold as 1967 model P11s, 1300 '68 P11As, and 497 '69 750 Rangers.
The P11s were about 40lb lighter than the G15/N15, and were as light as 326 lbs in racing form.