There is a B&W photo of a Pearson 10M on the page for that model. This photo is very unusual in that the boat appears to have a staysail set on an inner forestay, or Solent stay, something that was not standard and was probably a retrofit? Or did some boats come from the factory with this? Also somewhat unusual in that the boat is flying an asymmetrical spinnaker instead of the original symmetrical.
Do you have any information on the particular boat in the photo, and/or the owner? I'm interested because I would like to install a solent stay or staysail stay on my 10M and would like to learn details of how it was done.
Pretty sure this photo is from original brochure. I don't think this a really an assym. You just can't see the pole. A spinnaker of this type was called a star cut, simply a very flat symetrical spinnaker with verticle/radial panels.
To fly a jib like you see in this photo you could just mount a pad eye with a substantial backing plate. It looks like the luff is being tensioned on its own wire or rope. and is set from the standard masthead halyard. If you planned on sailing the boat upwind like a cutter. Than you would need something more substantial.
There used to be a Pearson 10M group around somewhere. try searching.