When I did VDO gauges in my 67 barracuda, I clipped the round connector on the dash and terminated them with molex-style pin connectors.. I used a 12-hole connector from Radio Shack and crimpers to create my own dash harness plug.. If you go my route, buy extras-- they never give you enough barrel and pin connectors to screw up in any way :)
I used the original factory wiring for the sensors (seemed easier than running my own wire), as well as a painless dash wiring harness.. It wasn't painless, and it certainly wasn't clean.. The next time I do a dash (soon enough-- the slantillac needs good gauges and I happen to have these VDOs laying around after a kid wrecked my parked barracuda..!) I'm going to do my own dash wiring.. The Painless set-up wasn't worth writing home about.. AND, tons of extra ground wires I didn't use.. Maybe its because I used a 4-in-1 marine gauge.. all 4 gauges grounded commonly..) In
Long answer to a short question-- nah, put the circuitboards on a shelf somewhere so when someone with a factory dash breaks a pin, they'll be able to just pop yours in instead of doing the fool's errand of trying to repair 40 year old circuit boards.. :)
Not to high jack the thread, but if you are using all aftermarket gauges, is the circuit board the was originally installed even need? I assumed that once all the gauges were hooked up, the original wires and circuit board were trashed??