A&K M-249 saw para

I just have purchased an A&K saw M-249 saw para and i wanna upgrade it fully can someone tell me what to buy and what brands please it would be a huge help i love this gun just want it to be really bad ass thanks for any and all help

so im gonna put an M140 springs, supercore pistons, magnum motor, rewire to 14 gauge and deans, mosfet, chrome moly pinion.
but i need help on what kind of gearbox i should get with it and the size of battery i should use

(don't double post)
the m249 comes in both v2 and v3 gearboxes. It doesn't say which on the A&K type (CA type) (CA type is CAPE Ca pre upgraded)

a side note
FPS at 425 may be shooting too hot for some fields (check first, otherwise $ dissapears)
and do you have any skill on upgrades?

no this will be my first time upgrading by myself but i figured it couldnt be to hard if i took my time

it is hard, I wouldn't try to do it without help, otherwise the next post after will be (and 99.9% sure) will be in ask a pro

'HELP MY GEARBOX EXPLODED ON ME'

I'd send it to someone to upgrade it, or start with a TBB and new hop up
not attempting to go evil but thats what I figure would happen

but still looking for the v2 vs v3 for you

i wouldnt know where to send it and i don't know the cost

airsoft gi has a tech department,
http://www.airsoftgi.com/index.php?cPath=67_68
find which one you need