I think it's a good project your embarking on Mike.
9602's have always been a difficult chip to find.....just for the record i have around 150 of them new that i sell at $4 each....i think this is a pretty good price considering the chip is no longer made.
You could also go down this path and use a 74HC4538 in place of the 9602
This guy here has done and documented it
http://home.pacific.net.au/~jennyah/4538%20Bally%20Clock.htmIt shouldn't be hard to work into your board design
