YJ-18 is the normal bread and butter anti-ship and land attack cruise missile for type 055, it has 540km range and carries a 300kg warhead. It's subsonic for most of the flight, accelerating to mach 2-3 on final sprint to the target. By all account it is a very formidable anti ship weapon.
The Chinese VLS standard (GJB 5860-2006) calls for a cell of 0.85m x 0.85m, with three different depth available much like Mark 41. Type 055 has the deepest implementation at 9m, the next deepest is I think 7m and the smallest one is 3.3m is. YJ-18 can also fit into Type 052D's VLS, which is probably 7m.
We don't actually know what range CM-401 has, guesses are anywhere from 300km to 1000km. However in its flight it's going to average mach 4 and on final approach it's mach 6. So it both reaches it's target quicker (despite greater range) as well as harder to intercept due to it's much higher final attack speed. Also look at the current CM-401, it's a very stubby missile and I would guess it would actually fit into a 7m deep VLS cell. A stretched CM-401 that takes advantage of the full 9m cell of Type 055 would be a very high performing missile due to its size. A ship based missile of this size is not currently possible on anything other than a Type 055 because even the Mark 57 of a Zumwalt does not come close the the big VLS cells of the Type 055. Only way to have a bigger missile on a ship at the moment would be to put it into a SSBN.