The receiver you describe is what is commonly called the Colt "Transition", with 10,000 being purchased in 1924. The 60 on the right side of the trigger guard is the number identifying the Colt employee that assembled the pistol. The mark on the other side is the initials of the person in charge of accepting the pistol for the U.S. Military, Capt. Walter T. Gorton. The G encircles the WT.
Pictures would certainly help, but sounds like you have a post WWII conversion unit on the pistol.