I have the same rig as you - D70 with Ike housing and strobes, but I'm opposite in that probably 75% or more of my diving is in cold, limited-viz water shooting wrecks. Because of that, I needed to extend my strobes relatively far off the camera. Because the rig is also a bit negative, I went with some UCLS buoyancy arms to bring the strobes about 3 1/2 feet either side of my camera. I found in tropical waters (I was in Bimini this past August), arm length of about 2 feet was more than sufficient. I don't have an 8" port, but if you use one, the rig will not be as negative, so buoyancy arms may not make as much sense.
