Parts Sources
These guys are dedicated to old Chrysler hemi/poly engines, mostly for hotrod/show car type stuff.
Andy Bernbaum. Has a lot of old Chrysler stuff.
Lots more Chrysler stuff.
Parts for all makes.
Tires for antique cars.
Some parts, like caps and rotors, spark plugs, etc. can still be gotten at regular parts outlets like NAPA,
Autozone, etc.
Websites
Great forums about "Forward Look" (1955-1961) Chrysler models.
Nothing about Dodges, but a great site nonetheless.
All things Mopar.