California is a hot spot for parts. True, parts are getting more difficult to find, but with some research and some wtb posts here I am we can help you locate parts. Lotta members here with good used parts as well.
I was able to get pretty much everything I needed for my 305 v6 rebuild through O'reillys. That included:
Full felpro gasket set
Timing set with chain and gears
Oil Pump
Rod Bearings
Water Pump
Distributor
I had to get Main bearings NOS, same would be with cam bearings. I searched Ebay for those.
Cams are not reproduced anywhere that I am aware of, but they tend to pop up on Ebay in nos form as well. Or you could always have your reground which could lead to some mods.
Valves, valve springs, not entirely sure if those are available. The parts store guys around my area actually KNOW what they are doing so I can see if those are still available. Checked on summit racing's sight and no luck.
Pistons are not repopped, but if the ones in your 305 are ok I'd just re-ring them.
Someone will have to chime in on rings.....far as I know you could get them from Sealed Power.