The 120mm panaflo's you mean 1212l1a right 120 mmx38mm? Dude there noisey at least at 12 V forget about it!
I have two of those on the bottom at 6 V of my case and two nmb 119x25 b-10's on the top! At 6v they are unstable and forget about the panaflo unless your trying to go cheap I would personally recommend the nmb's but that's just personal experiance the best would be to go for nmb's or pabst but those are 20 bucks
Anyhow instead of two run 4 @ 5 to 7 volts there are some voltage regulators around here that will help you out there 5 might be a bit low 7 should be good enough that should give you a nice airflow and 4 fans of the same model at half the speed is less noisy that 2 fans at full speed!
anyhow 35 dBA is not that quiet. this guide might help
http://www.silentpcreview.com/modules.p ... =25&page=1
anyhow hope this helps