There is a book called The Depths of Space (Wolverton?) that details the pioneer missions, and includes some pictures.
I have found many, many pictures on the web, just browsing (pioneer 10/11, Jupiter, Saturn, etc...). Generally, the pictures were not as good as the wonderful images from Voyager. The 'spin and scan' method was necessary on the Pioneers due to the rotation stabilization that was employed (vs. Gimbled cameras on Voyager). But, that being said, they are still out there.
If you are really in a pinch, email NASA Ames, the folks who designed and flew Pioneer, and ask them for some assistance. I'm sure they will be able to help or point you in the right direction.
Pioneer was a great mission--I recommend the book....