Rear flash sync on 500C Body

This is just an idle thought, but my 500C has a PC socket on the camera itself. It's my understanding that it is tied to the auxiliary shutter-if I'm reading the manual right, it fires when the "doors" are fully open.

If I'm using an on-camera flash, I generally use a Metz 60CT-4, and I haven't wanted to pay Paramount money for cord that will let me use a quick focus handle with the on-lens sync socket. Plus, even without the QF handle, the lens socket is a bit ungainly. I also need to probably cut a piece of plastic strip or something to keep me from inadvertently knocking my lenses into the "M" position-I lost a few(not terribly important) shots because I switched to my 50mm and forgot to check it the last time I used flash with the camera.

Is using the rear sync port with my set-up a viable option?

Ah! We've all inadvertently bodged the XM lever to M. If you're sensible, it only happens once before you break out the gaffer tape, toothpick, chewing gum or whatever it takes to fix the stupid lever in the X position.

(And while we're on the subject, why is the darned caps-lock on a modern qwerty keyboard so near to the shift key?)

Can't help you with the body synch socket on your 'blad, but I suspect the flash will be over before the lens shutter opens.

As you surmised, the body sync socket on early 'blads triggers your flash when the body flaps fully open. But it isn't a very practical feature for normal photography: the "shutter speed" of the flaps is low: perhaps 1/8th second if you're really quickfingered with the shutter button or cable release. It was included to facilitate the use of special-purpose shutterless lenses like the Zeiss Luminars, attached to a Hasselblad via bellows and the 40037 dummy lens mount adapter. Hardly anyone actually did this, so the socket was dropped from all CM/ELM Hasselblads some time in the early '70s (then made additionally redundant by the re-introduction of bodies with fully-functional focal plane shutters).

Since there isn't any reliable flash timing communication between the body flaps and lens shutter, using the body sync to trigger a flash with a shuttered lens attached might be dodgy. I'd guess the lens shutter would need to be set to 1/8th sec or slower, so it remains open long enough for the body flaps to act as rudimentary focal plane shutter to fire the flash. Might be workable in a studio setup for product photography or still life? Or maybe not workable at all now that I think it through: the Hasselblad firing sequence has the body shutter fully open before the lens shutter begins to open, so the body sync would likely trigger the flash before the lens shutter opens, resulting in severe underexposure or blank frames.

I've always had it in the back of my mind to experiment with the body sync and a borrowed F lens like the 110mm f/2, but an appropriate subject never arises. Its on my bucket list.