Hello all, i just picked up a slim line and having difficulty identifying engine. From the research i have done, it appears heads are from the P11. Heads are stamped with serial 24237. Sound correct? Regarding engine, it is stamped with 20 / 122093 / P. Now, its my understanding the 20 refers to Atlas, but can anyone help me identify remaining? Thanks so much.

The part number you state does not sound familiar as a norton twin head. I have some info here that might help you identify the head. I am unaware of the low production twins having different parts except possibly for the primary bolt on pattern. http://atlanticgreen.com/nhth.htm 20 is the code for 750 atlas vintage motors. I forget when 20M took over... then 20M3 is early commando