I ordered a full J13 engine gasket set from RockAuto and it arrived this week. The 1.3 liter J13 engine came in the later 520 and 521 trucks and 411 cars from 1965-1969, but I expect that many/most of the gaskets will fit the E-1 engine. The set is Victor Reinz part #HS3597.
Here is a shot of the gasket set and its contents:
Below I will inventory the gaskets included for posterity.
Valve stem seals:
Valve cover and inspection cover gaskets:
Combination intake/exhaust manifold gasket (note that it is a perfect fit for the E-1 manifolds):
Carburetor insulator block
Note that the J13 insulator (right) has a single large oval-shaped opening to match the J13 intake whereas the E-1 intake manifold and insulator (left) has two separate circular openings:
There were the two intake/exhaust manifold gaskets. The slightly larger one is the hot spot gasket that mounts on top of the exhaust manifold and mates to the underside of the intake manifold (same gasket shown in both pics below).
Water pump gasket:
Fuel pump gaskets (two, one goes on either side of the fuel pump spacer, not included in this kit). These gaskets are also available separately, Beck/Arnley part #039-2008. Likewise, the fuel pump spacer is Beck/Arnley part #039-2002.
Thermostat tower gasket (also Beck/Arnley part #039-0004):
And, importantly here is the J13 head gasket: