Sounds right to me, too.Should eryops be aquatic with amphibious ability (since it is an amphibian, after all)?
Hm. Give it a better Swim speed, worse land speed, and the suction feeding as per the Dinichthys conversion. Suction feeding is a good ability; giving it another HD and/or boosting Str and Con a bit should bump it up to CR 3.
I wouldn't increase the size. Paracyclotosaurus was six to eight feet long--on the big size of Medium, but still Medium.
Of course, Large would make it scarier and the suction feeding more useful... so I can see the appeal for game purposes.