I have three of the Chinese '97s. I am well pleased with them. They are reliable, pattern well with buckshot and seem well made and fitted.
You will not touch an original trench gun for anywhere close to the price. Yes, you can find used '97 sporters and riot guns but original trench guns are $800.00 and up. WAY up. And if you did fing a decent original, you'd have paid so much, you'de be afraid to shoot it. If you want a fun gun that you can enjoy, or even keep for defense, the Norinco is what you want.
BTW; 2 of my 3 are trench guns, and both took an original Winchester made 1917 bayonet withoug the slightest fitting required. You should strip the gun down and clean the preservative oil out of it and lube it properly. And be sure to tighten the barrel shroud screws good.