If you want to install SL7 compression ring, you need to order also SL7 specific bearings. AFAIK the bearings provided with the frame are not exactly the same, they have a different internal diameter. Outer diameter is the same, in order to fit on the frame.
SL7 bearings can be found from realiable brands or also on any specialized store.
I consider that it is a good idea to install good quality headset bearings on frames like this. If you need to replace them, you need to disassembly all the hoses, quite a mess. So better get good ones which may have less maintenance isues.
Personally i purchased bearings from brand Black Bearing.