Here is a pic of my setup.
Atomicrider - that is a really nice looking frame. Is it stainless? Polished?
66" frame width sounds like a good compromise to me.
As for oar lengths - those are determined by the oarlock to oarlock distance, seat height, tube size, oar spacing (overlap or gap of "x" size) and rowers height. Boat width doesn't really matter.
Shorter oars on a setup that is otherwise identical (based on the variables listed above) results in a higher engagement point (how high your hands are when you take a stroke). Longer oars result in a lower point of engagement (and less mechanical advantage).
Oar length should be the last variable you solve in your setup. Determine your preferred seat (cooler/drybox/flip seat/seat mounted on cross bar/etc) and how high that makes you above the waterline on your boat. Then determine the oar tower height you need to clear your knees. Next decide on the oar overlap or lack thereof you prefer - I recommend a gap of about 2-3" (this prevents banging your hands/thumbs together and allows for your oars to not knock you out of the boat as often). With that info in hand you have two choices - do some trigonometry to determine ideal oar length - or call a raft shop and get some advice.