64s are like "hen's teeth" today. At about 84 CCs, they are ideal for a 9.5:1 400. They're quite valuable to the collector crowd, as they're the only casting that was on '70 GTO 455 cars. 13s with a small "dish" in the piston are every bit as "good" a place to start.
Good call on hanging up... (:- It amazes me how the "younger set" isn't versed in older engines. When I was a young man (early '70s), it was VERY important that I knew the flat-head Fords, the early '50s OHV Olds, Packard V8s, 216 and 235 Chevys, etc. Most of these were already "gone", but knowing A) they existed and B) how to repair them was a necessary part of my job.
Vic Hubbard Speed and Marine used to be in Oakland or Walnut Creek (memory is the 2nd thing that goes..). He was THE Pontiac "guy" in that area in the '70s. If he's still around, he can probably point you to a good shop that will KNOW the Pontiac.
Woodland, huh? I used to work for the man that owned Woodland Rent-All. He had stores in Vallejo (where I was), Fairfield, Vacaville, and Auburn. NICE area! Haven't been there in many years, though. I was a member of The Brotherhood of Streetracers, Vallejo Chapter!!! My GTO was the only non-Chevy in the chapter, and it was the KING of the street-legal cars among them. They hated me... (:-
Jim