what colors were availble. where is the engine stamped

What year?

1963

You can get an original factory sales brochure cheaply on Ebay, which will show you the available standard colors. Often dealerships would allow orders for different colors, like Mary Kay Pink, or previous year or model colors -- Say someone wanted a Grand Prix to match their 1959 Cadillac, it could be done for a price through a Central Office Production Order, or COPO. The engine should be stamped somewhere on the block itself, cast into the iron of the block. You may need to remove the engine and power-wash it to actually see the casting after 44 years of grease and grime.

The number is on the front of the block left of the water pump when facing the car. This number should match the stamped plate riveted on the driver door frame where the hinges attach.