DrG
Are you feeding a low pressure or high pressure pump? We have a #10 line from the tank to a Holly red, about 10 inches and pump is mounted even with the bottom of the tank, then 5 feet of #8 AND a large filter feeding the high pressure fuel pump. High pressure is a #6, return is a #6, vent is a #8, Fuel tank is filled with Fuel Safe foam.
Of course we were feeding 1 liter when we designed it, now we feeding 1.5, but it seems to be doing OK, never had a starvation or cavitation issue...
Hope this info helps, try to deliver way more than you need