zippy r lipos are they enough???

hi guys. i have a Losi 8B with rc-monster mount, RCPD battery tray and esc mount bit i have a quick question.
my setup is a medusa 36-60-2000kv motor, mamba monster esc and zippy-r lipos (along with some 5000mah 20C ftx lipos).
the only problem is the zippy-r lipos are huge (about 175mm long) and i have had to use a homemade battery mount to mount the 2 4s packs in parallel for 9000mah = alot of runtime
i think they are 21C/35C bursts but can anyone confirm this?
together for the pair they weigh about 900g so i would like to have to only use one and it would be easier to mount so will 21C continuous and 35C burst be enough for my setup?

thanks richard