Timing question

I have a 94 Sport Nautique with the Ford 351 and a PCM PROTEC ignition and throttle body fuel injection. The PROTEC has started to give me a lot of angst of late primarily with wanting to come up in a mode with a very high idle that never comes down. Then randomly on a different day it will act just fine, idling and running normally.

I have checked wiring and such, but my suspicion is I will have to finally do the conversion back to carbureted with electronic spark. I am pretty comfortable in doing this with one big question, timing. About ten years ago the balancing ring broke and fell off the motor and I think the timing marks were on that as I cannot seem to find any other marks on the flywheel to go by.

Any good ideas about this? Is there a replacement ring I can get? Some other way of putting timing marks?

Thanks to all.

So do i read this correct you have been running 10 years with a compromised harmonic balancer?

If so, best begin by replacing the balancer

Fantastic way to prematurely wear main bearings and timing sets too.

As long as the TBI ithrottle plate is closing fully, this doesn't yet sound like the typical protec failure modes.

Verify the throttle linkage is adjusted so it applies positive pressure to close the throttle against its stop.

Alternatively, perhaps something is causing the protec to go to full advance, or stuck at a higher advance. I'm not privy how the protec advances, if its entirely electronic or if there still a mechanical component to it.
That would raise the idle similarly.

I suspect the bulk of the 50oz corrective unbalance is cast into the core of the balancer that remains, then the ring is fine tuned, you can see some drilling on the inside edge that faces the engine.

But as been said, reinforced and reiterated, replace the fractured balancer, its not there just to look sexy, it suppresses harmonics that lead to catastrophic crankshaft failure.