I'd never heard of double super 8 so I looked it up on wikipedia--its 16mm film with 8mm sprockets--you seem to need a special camera. You load it on one pass and then reverse it for the second pass. It gets split into two regular 8mm pieces on developing.
Otherwise, it sounds like you've answered your own question. Get some of each and shoot it and see what it looks like.
Do you have a digital camera that has ASA settings? You can use that to see how much light you need for the 8mm. Do you have the camera and know how fast the lens is and what shutter speeds are available?
The 200 or 160 should do available light reasonably well.
This was a long time ago but I'm pretty sure it was shot on plus x (100asa) with two mongo (1kw) lights.
http://www.youtube.com/watch?v=HzRHySNtf0o