65 Cuda, 273HP

My friends 65 Cuda has a vacum canister about the size of a loaf of bread mounted on the inner fender, is this to help the dual point distributor. It's a 4speed car too if that helps.

That’s a back up to the power brake reservoir, it’s a power brake car right?

I'm not sure if it has power brakes.I'll call my pal and report back here.
Should there be a check valve?

Yes, there would be a check valve