Yes, it will fit. The 2 piece shaft was done to avoid any misalignment due to poor block machining.
FYI
Shaft diameter is only relevant to fitting the gear onto the shaft. It has no bearing on fitting the distributor into the block, or how it interfaces with the camshaft, unless the fit of the gear to the shaft is loose. The only time you would need to change the gear is if its bad, or if you need to change to a bronze gear for a specific application, like a '54 or earlier factory camshaft for compatability issues.
