Well, I haven't gone back to the 62 yet, I have been short on time.
I started tearing it down for flat black. I am spraying it tonight, but this entire tank has been the 64, so I will leave it with 64 jet for the test.
When I installed a Holley re-man on the 73, fuel mileage plummeted. When I checked the carb, it had a 62 jet, where my shop manual said it should have a 52. I re-built the carb, correcting a float problem in the process, and changed the jet to a 52. I cleaned and gapped the plugs, too. The changes have moved me from the low teens on the highway to the mid-twenties.
The engine has 190K on it. Compression is low, it runs notoriously cold. No manifold heat. It has an oversize exhaust manifold and a 2¼" exhaust system. The transmission is the original 904G, still in good shape. The axle is a BBP 7¼ with 2.76:1 gears, 205/60-15 tires.