i can fit a 9v battery in there(do you need a 9v per PU. e.g. one for neck and bridge?) but is any more stuff you need with actives then just a 9v? (first time changing pick ups)

(and sorry for bad quality, it was taken with webcam)
better shred than dead
If you can place a 9v battery in there without force and crushing other components. That should be all the room you need. If your buying a set of pickups then you should only need one battery. You'll need 2 if the set is split and you can't work out wiring the battery to a series. Also, the pickup set will probably come with different pots which sometimes can be larger than the originals.
If the battery can be wrapped in foam and placed comfortable in the cavity, Your fine.
Quote by shredda2084
i can fit a 9v battery in there

you answered your own question.
Quote by shredda2084
do you need a 9v per PU. e.g. one for neck and bridge?

of course not. Have you ever seen an EMG wiring diagram? Both pickups are connected to one battery terminal, for 18v you would then connect the first battery in series to another battery terminal. Looks like you have plenty of room in there, but if not you can always get rid of the tone control pot.

"Show me war; show me pestilence; show me the blood-red hands of retribution..."
if your changing from passive to active then you'll need a new jack (stereo) and new pots (25k) although they should come with the EMGs.