The first order of business that I take is to tally up what is in your cabinet still that came from the factory, then make a list of what is missing and start getting prices on what you need and then posting your wanted lists online, fellow hobbyists can often help you find what you need.
Is the original sideart under the black paint? sometimes it is and if so it often can be uncovered using citristrip.
One option you have if there is nothing factory left in the cabinet but it's still solid is to look for a junk complete cab (water damaged, mouse nest smelly, ETC) and simply transfer everything over, Or you can start picking up parts one at a time as you find good prices. You can even sell of the current marquee, bezel and PC board to get some money for original parts.
Since the Centipede PCB is missing you may want to consider buying a Millipede PCB and the Multipede kit, this fits onto a Millipede PCB and lets you play both Millipede and Centipede. it's a nice option, and it's what I'm doing on my Millipede, here are details on that:
http://www.brasington.org/arcade/products/cm/Hope some of this helps you, good luck with your project.
