Utilize NOS (new old stock) parts wherever possible, using "new" obsolete surplus computer chips and digital displays from the 1960's and early 1070's.
Keep the circuit topology time (era) coherent, no hi-tech chunks "dropped in" for fancy things, keep the clock design pure to a "slice in time" (late 60's-early 70's).
Circuit designed around popular and available chips, very robust and conservative.
Keep the circuit quiet and "noise free", no switching power supplies, multiplexed displays or micro processors.
Keep all parts and manufacturing as local as possible, American parts and manufacturing wherever possible. All chips are made by Motorola, National Semiconductor, Texas Instruments, Fairchild (all American Companies). Circuit board is manufactured in Chicago, IL, Plexi-glas case fabricated in Philadelphia and all assembly is performed in Wayne and Norristown PA