My diesel tech instructor mentioned he had a '61 matchless he was looking to unload. Not assembled but with two engines, two trannys, and with all else thats necessary plus some other extras (2 sets of wheels, one set trued, one not, extra headlight, forks etc) Basically 2 bikes with one frame. I dont know much about matchlesses other than they make me drool. He said it was a single but in my brief search on google Im finding no '61 singles. Just a twin. The g12 I believe. Got any info for me on their '61 single cylinder offerings, design shortcomings (im already aware of the lucas electrical issues), etc?

I owned a 1965 Matchless 500 single back in the day
It was a model 500GS and was very little changed from it on back to the same model issued back into the 50s.
It was 4 speed with a high torque engine. The bore and stroke were the same square.  It had an Amal carb with a separate float bowl.
It was capable of very nearly 100 MPH on a flat road with no wind.
It handled curves magnificently but was a little under braked by modern standards.
To start and ride it you needed to understand the carb tickler, the choke ,the manual spark advance, and the manual compression release.
It was not necessary to understand pain, any missunderstanding of the above would result in the kick starter instructing you about pain.
By all standards a Magnificent ride once you got on first name basis with it.  It had hairpin valve springs and the valves were easy to adjust.
Clutch was semi dry and easy to service.

Phelonius