The CYMA M14 is a clone of the Tokyo Marui M14. The TM M14 has a special hop up unit, and a special V7 gear box.
The M14 hop up has the barrel retention cut outs in a different location than other AEG's. Most barrel manufacturers make the proper barrel, you just need to make sure to buy the correct one. For example, this
is the barrel you want. Great barrel choice by the way.
The hop up takes normal AEG buckings, so the Systema bucking will be fine.
TM put an elongated cylinder in the M14 to support very long barrel lengths. Because of this you usually need to go up one more level of spring to reach a desired FPS. For example a spring that shoots 400fps in a normal AEG will shoot 380 or so in the TM M14. I'm not sure what FPS you are aiming for, but keep that in mind.
Searching Google I could not find the AIM piston and gear sets very easily. My guess is they are V2/3 and will not work in your M14. You will need to look for a gear set that states they are TM M14 specific, like these
. Because of the elongated cylinder you will need a V7 specific elongated piston. I don't know of a good one, but here
is an example of what you need. There is a way to convert to normal pistons if you search the web.
The shims are fine as all gear boxes use the same shims as far as I know. I know for a fact the CYMA M14 uses normal ones.
Make sure the suppressor is CCW. The RAS will work, however the RAS is designed with the use of a scope in mind. An ACOG will have to be mounted in front of the bolt. Personally I think that would look sort of weird, and I'm not sure how easy it will be for you to see out of. I noticed you picked out a non zoomed red dot style, so eye relief shouldn't be a problem. If you want to use an ACOG I would recommend a scope mount like this
. It will mount the optic over the bolt and make it easier to use. Lastly, I don't think a 4x ACOG mounted on the RAS would have enough eye relief for you to use. If you do a search on Google for "M14 ACOG" you will find the propper mounting point and hopefully see what I'm trying to explain.
The high torque motor will work, just make sure to get a short type. You do not
want a medium or long type as they will not work.
Lastly, I highly recommend the Guarder steel cut off lever
. The factory cut off lever is made out of very cheap soft metal and will wear down quickly and leave you with only full auto. It is not a matter of if, but when it wears down. My team mate had his CYMA M14 wear the cut off lever down in less than 20K rounds. Another person I know had his TM's wear down in less than 30k rounds. Do yourself a favor and replace it while you're in there.