DonO, your car is listed with theft-proof and vehicle number in my database but sorry to say, no prior owner information.

A good place to start if you haven't already done so would be with the Packard Club roster keeper for 1934 Twelves. If you provide the theft-proof number I'll check my database which is quite extensive for 1934.

Even a collapsed hydraulic lifter will still allow the valve to open and close sufficiently for the cylinder to function.

A minor point of correction, hoping you don't object. Your car is not a Standard Eight. Its properly an Eight, though you could call it a standard Eight if you wanted to emphasize that it wasn't a Super or Custom Eight, but it is not a Standard Eight. The word "Standard" as part of a model name was dropped after 1932.

Yes, the blower motors are normally very quiet but the lack of ammeter deflection would suggest it is not functioning.

384 cubic inch is the Super Eight, 320 cubic inches the Standard Eight.

I'd think it unlikely that fuel could run back from the carburetor bowl thru the pump to the tank, isn't the fuel in the bowl at a lower level than the fuel inlet? I'd consider a non-functioning fuel bowl vent which would allow the fuel in the bowl to percolate out thru the main jets into the manifold and then evaporate.

Thanks for the clarification, I'm not familiar with that cap and wiring technique. Pictures?

Do you really mean wires that end with a thread and screw into to cap, or perhaps wires that terminate with an eyelet and are attached to the cap with a machine screw?

If the latter, that's typical of many distributors from many makes of cars from the early years up to the mid-30s. My '34 Packard with NorthEast distributor uses high tension wires terminated with eyelets and attached to the cap with machine screws. The spark plug end also uses eyelets attached to the plug with knurled thumb wheel nuts.

Pulfer and Williams, part of LaVine Restorations.

http://pulferandwilliams.com/Packard/

From what I can see in your photos, the passages on your gasket matches those on my original Packard steel factory gasket, suggesting the reason for your overheating lies elsewhere.