I had bought 2 from kinneys, they are alright, but be prepared to do a bit of milling on the end of the rail, the 5 rifles I tried the rail on wouldn't fit because the dovetail on the 527 reciever was not milled the entire way. I milled the dovetail off the end of the rail to fit and it fit. The major thing I didn't like it's how the rail lined up with the stock end of the reciever, so I ended up making my own.
The Kinney will get you out of a bind and is rather inexpensive, but if you can get your hands on the cz one, I'm sure it is much better fitting