TOPIC: '72 Evinrude 65hp info needed

OK so I broke down and decided not to part the '72 but to get the ol' girl running. What I need is the length of the spark advance link. The rod that connects the long lever to the advance under the flywheel unless someone is willing to donate Easy to make but at what length.
The other situation I'm working on is the shift button configuration. Since I have the wire harness up to the missing control box it's easy to add a choke button and ign switch which I already have wired up. What I need to do is jump a wire from the choke power feed to the shift to she won't start in forward. I'm considering using a switch from a car side mirror control. You know the kind, left, right, off in center. Use the "off" position as forward and wire the left/right rocker for neutral and reverse. Any opinions?

Part number 314165, still available thru Seaway. About $18 at an OMC dealer

Thanks for the part number. Local dealer did not have it. Found one on Ebay, the whole linkage setup with rods, levers, bushings etc for $16. and free shipping out of FL.