They're out there, but there are many that won't help.
Many were only made for 15 bolt blocks.
Both iron and aluminum.
Some can use a reground or aftermarket stock cam, some need a billet cam.
Both manifolds are very tough to find and identify.
Head gasket?
Some have 12 ports, but the chamber was obsolete 80 years ago, and need $$$ pistons for any compression.
Any aluminum part may have corrosion damage.
$5,000 will get you started
