We have processed seven rolls of 135 film at a time using 800 ml of solutions, using Fujihunt 5 liter kit, with no problems. That is very close to your situation. You may need to use a little longer development time to compensate. I would say 10 seconds extra. Look at the Fujihunt kit instructions how much time has to be added after how many rolls: http://sorsa-tv.ath.cx/~antalh/fuji_ohjeet.jpg . These instructions state that when using 1000 ml to develop 100 ASA 220 rolls, you have to add 10 seconds after 3,2 rolls developed for the next 3,2 rolls. So, 10 seconds would make sense for six rolls as one-shot. 400 speed films would need about 15 seconds extra instead of 10.
Look at the replenishment rates from the Kodak documentation, it certainly will not say one liter per 220 but probably something like about 100-150 ml per 220. Check it out.