I don't want to discourage you because this seems as a very interesting project, but I want to mention some potential problems you may want to keep in mind.

The typical Chinese actuators (rails, carriages, etc.) are not suitable for high speed applications. Not to mention the notoriously low quality control. Be prepared for some disappointments with this.

The heads offered on cloudraylaser are for cutting. My honest opinion is - Unless you are willing to design you own head you won't be able to achieve stable scanning speeds anywhere near your target. Take a look at some of the high-speed machines and the head design they are using.

You haven't mentioned what type of laser source you intend to use but I am assuming it will be a DC (direct current) tube. The DC lasers suitable for cutting are not a good choice for engraving and vice versa. The problem is the power fluctuation especially during ignition.
RF lasers are the ideal solution as they don't suffer from any tradeoffs but are quite pricy... Personally I consider using a RF laser "it's a must" for good quality engraving.

I am concerned that using expensive SERVO may be an overkill when combined with typical low-end Chinese components. Using inexpensive Steppers maybe just fine in your scenario. By the way this is the reason why the Chinese factories almost never use SERVOs.