need help with converting a hyper 7

[whitrzac]

I'm no newb when it comes to RC, but this is my first atempt at converting a 1/8 buggy, and I'm trying to do it cheap

my gear so far
tekin RS pro esc, with diffrent caps, and an external bec/rx pack
novak HV 4.5 motor
this motor mount
some misc. mg servo that I have laying around
true rc 5000 hardcase lipos/protek 4000 lipos/gp3300s


I only have the esc/batts as of now, but I'm seeing a problem on WTF to put the batts, I origanaly planned on haveing 1 pack on each side, but there too long to fit behind the diff, and too wide to fit on the side of it without riding up on the mudgaurd...

I still want to keep a "saddle" pack layout, but I have no clue on how to mount the batts.

I have basic tools to fab some parts up, but I would prefer somthing pre made


what kind of preformance/speed/gearing should I be looking at? it probably wont see any track time...

link to the motor
http://www.teamnovak.com/products/br...kits/OFNA7.jpg

mabey somthing like this? http://cgi.ebay.com/NEW-SAVAGE-FLUX-...QQcmdZViewItem

would both of these fit on the chassis at once??
http://www.shopatron.com/product/par...56.35136.0.0.0


just an observation, why does a 32p pinion cost $4, but once its been drilled out to 5mm it costs $10-$15...