Ok here it is. Oh BTW I didn't answer your question about that broken piece you found... Yes that is the ACR.... I might have your cam in stock.... I'll look in used parts section..
Here's the link.. There is a comedy skit at the beginning if you want to skip it....
https://youtu.be/dWHPHGZAvj4
I viewed the Video for installing the Camshaft. Seems to me to be clear and especially the alignment positions.
I checked another engine part witch (to me) seems to be rather Fragile and believe it must be the governor since it connects to the outside carburetor area. This item is also damaged (broken) and will need to be replaced.
Earlier today I did some lookups regarding available parts (camshaft, seal, mid engine gasket, head gasket. etc) and the camshaft plus gasket and the two "stems" that the cam rubs on -- and the prices range from around $40. to $65.
I may not need the Head Gasket.
I have not searched for the governor.
You indicated you may have the cam. Regarding shipping -- Where are you located and have you priced it
Note: the risers on the camshaft don't show any type of ware due to usage. I got this Mower used but without the mower deck and close to 2 years later got the Junker YTH2348 which had a 48 inch mower that could be repaired, welded, etc plus it had an automated clutch assembly -- both of which ended up on the original YTH2042 mower and worked well until this engine problem.
Let me know if you have the mentioned parts and pricing.
My Regards, Vern....