We extend to you a cordial "WELCOME ABOARD !" Come on in, make yourself at home, we are a friendly group of enthusiasts, and we also appreciate the classic Chris Craft Roamer, Corsair, and Lancer boats too , as they are all on the same family tree and share much in common !
My 1968 35' Sea Skiff did not have neutral safety switches, however it did have a pretty good second choice which I found to be quite useful.
These are available in kits I understand.
Upon twisting the ignition key you would hear a loud bell under the engine compartment, so loud that you could hear it while under way. You would silence the bell by pushing a button on the dash, not unlike a horn button. Upon silencing the bell and twisting the ignition key further, the starter motor would engage and the engine would fire, at that time oil pressure would keep the bell silent. What I liked about this system, installed by CC or a previous owner, is the fact that if you lost oil pressure on an engine (as in a stalled engine or low oil) then the bell would sound off and alert you to the issue.
No bell on board now, but of course the very first thing I do religiously upon reaching for ignition key, is to be sure gears are in the up (neutral) position. I also always take transmissions out of gear while at rest with engines off. With kids on board of all ages, I still always check gears before starting.
Unfortunately many years ago in a mahogany runabout, I started a Hercules powered runabout in gear, and the guy in the boat in front of me did not appreciate what my bow did to his boat. That was tough to live down, because I was an organizer of the event, sheesh, sometimes you can't win for losing!
I am interested in knowing about your search, if you find a retrofit kit, please post it here as there are many people who would probably want to add one.