The Volvo shop manual gives no spec for end play. They must assume you'll be re-assembling the distributor just as you disassembled it. You probably had one of the fiber washers fracture and drop out the the assembly along the way. Volvo does not sell new fiber washers, but I have some from old distributors, and some from a local hardware store. I can't give you a figure, but I probably shim the end play from 0.000" to 0.008".

Once the distributor is installed, the shaft tip o-ring provides enough friction in the cam socket to prevent end-play. Your distributor does not have Hall effect, and the only thing end play will give you is more or less clearance between the rotor and the cap. I've overhauled many distributors, and I generally don't install new shaft tip o-rings unless the old one has been damaged. They only provide friction in the socket of the cam. They cannot leak any oil because there is not where for the oil to go.

Volvo calls for a new pin to be installed every time the distributor is apart. I've never gotten a new pin, but I've dressed a few.
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john