As far as I know they were good engines. Should be a looper. The loop charged engines were great engines...I have a crossflow...but I love the old girl. The later 90's and into the 2000's is where you find trouble...until BRP took them over.
If you are unsure...have a compression and leakdown test performed. Check the lower unit for water..(white fluid)....and take her for a good run if possible. I would not buy it if it didn't have AT LEAST a compression test done on it. As leakdown also would be nice...and by all means check the fluid in the lower unit.
"But if serving the Lord seems undesirable to you, then choose for yourselves this day whom you will serve, whether the gods your ancestors served beyond the Euphrates, or the gods of the Amorites, in whose land you are living. But as for me and my household, we will serve the Lord.” Joshua 25:15