Thanks for the solid advice guys,
Sitting Duck - I've also heard some good and bad things about the Ares gearboxes however I have a couple of friends that have some of the newer RIF's that have the Gen3 V2 gearboox with the EFCS and they've run really well over the last year and a half which bodes well. One of the things that the G&P needs is a Mosfet so I can run it on some 9.9v LiFe batteries so getting a complete Ares gearbox solves this due to it having the EFCS built into the trigger section of the case. Another draw as the micro switch is really snappy on them (although I know this can be a bone of contention) which would be gained from going this route.
Completely built I can get one brand new for just £75 delivered which seems like a decent price on an item like this that normally goes for around £100. Adding up a custom built gearbox with shell and all internals adds up quickly and will take up a bit of time building.
I could keep the original shell and upgrade the internals, it could do with a new cylinder head, piston and piston head, and then an AB Mosfet as well as a rewire. All in all, that's going to come in more expensive than buying a complete Ares gearbox. Although it does mean that this would make a pretty nice project to work on over a number of months as I guess it doesn't hurt to have a spare.
TheGrover - I'm fully prepared to do a little work if needed and have the Dremmel on standby but hopefully it won't be too far off with fitment.
I'm a little rusty on my Asian languages but I managed to turn this up on some searches this morning so it does look like it's possible to fit but then there's no telling if the guy is listing off a plethora of modifications he had to make to get the sucker in there!
On another note, does anyone have any recommendations on a decent motor? I play semi auto on an M90 to M100 spring so no real need for anything that's going to be able to pull an Ox or provide an insane RPS.
Thanks again,
K