You need to modify the Mato elevation unit. It has a stop on it that needs to be removed so the gun can cycle up and down with the HL electonics, iF you are keeping the airsoft the Mato gun can be used. If you are adding recoil, think about using up your spare Tamiya unit,

Yes you will need an RX 18 if you want to use the DBC3, Mako or IBU units,

Find a way to add the Mato metal suspension. It is more to scale and works great.

Cheers