How to adjust timing if you can't see the timing marks?

I have a weird situation and would love any creative solutions people may have:

My Duster has a 360 magnum crate engine that I bought used - it's in great condition and runs strong. However, the previous owner had installed a serpentine belt system, I believe from a Jeep Grand Cherokee or something. Anyway, it works well but almost completely obscures the timing marks on the timing cover. There is the tiniest little opening you can look through to see a part of the timing cover but you cannot shine a timing light on it at the same time you look at it.

I'd prefer not to switch out the serpentine belt - if it ain't broke, don't fix it, right?

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Get a piston dead stop tool and set the engine to true TDC...

Then make a reference mark on the engine where you can see it, and then make a corresponding reference mark on the harmonic balancer... Now those are your new timing marks....

Summit RacingĀ® Piston Stops SUM-900189