Hi Jerry and welcome to the forum.
The front drive gear for the 25 is lubricated by the engine oil that is supplied through a passageway in the front of the block. Therefore, when you reassemble, it would be advisable to place a very light coat of grease on the gear to lubricate it till the oil starts flowing again.
Don't concern yourself with any timing marks when you bolt it back up. The timing is done later with the distributor and distributor cam. Locate the #1 piston on the compression stroke. Orient the distributor so the spark linkage is correct (in the full retard position) and the rotor is pointed to the number one plug wire contact on the cap. Loosen the nut that holds the distributor cam and move the cam so the points just open with the rotor still pointing to number one on the cap. (It is assumed that you have correctly set the point clearance prior to installing the distributor).
Sounds easy, but sometimes becomes very frustrating. Just stay with it and when it is correct you will :)
Wish you luck on your project.
RAY Chevradioman http://www.vccacolumbiariverregion.org/1925 Superior K Roadster 1928 Convertible, Sport, Cabriolet 1933 Eagle, Coupe 1941 Master Deluxe 5-Passenger Coupe 1950 Styleline Deluxe 4-Door Sedan 1950 Styleline Deluxe Convertible 2002 Pontiac, Montana, Passenger Van 2014 Impala, 4-Door Sedan, White Diamond, LTZ 2017 Silverado, Double Cab, Z71, 4X4, White, Standard Bed, LTZ If you need a shoulder to cry on, pull off to the side of the road. Death is the number 1 killer in the world.
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