Did not the 88 use a rimmed cartridge as well?
I also heard that many of the 88 receivers and barrels were not heat treated. It is dangerous to fire an 88 without first having it proofed through a gunsmith who has the equipment to do it. Xray is reccommended.
I also heard that some 88 rifles were pressed into service in the second war, late in the war, and they had been re-barrelled or re-configured to use the 8mm JS round in a single-shot fashion. I dont know if that is true or not.
The 88 is a damned interesting collectible. It had some wonderful engineering in it for it's time. It was vastly superior to many other rifles in service at the time. But there are limitations in these guns that have to be respected. These 88s were shipped all over the place in a variety of conditions and they were cut out on a variety of machines. You can find them in Asia. You can find them in Europe. You can find them in a variety of conditions cut on many different types of machinery by smiths that were not always in the employ of Mauser. The steel can very from lot to lot.
You need at this time a well educated and experienced gun smith. One that is into the Mausers in a big way. Have that rifle checked out completely. Pull the information on it, and pull the history on it, as well as the condition.
You might well consider not to fire it. Just hang on to it as a collector, and find yourself a good Russian capture 98K mauser or possibly even a Jugoslav to take to the range with you. They are accurate, fun to shoot, and worth hanging on to. Put the 88 up and save it for your collection.