A couple of things B&P's. 1. The max in the 50lt malt pipe is about 13kgs. You can sparge this and get about 65lts pre-boil and then boil down for minimum 2, maybe 3 hours to get a fairly high gravity. (50lts after 3 hour boil?) You would need to do an hydrometer reading to see where it is at and then adjust with malt extract (maybe some sugar) to get your starting gravity. Putting the numbers through software would be essential. I haven't done this, I'm pulling this stuff out of my head as to how I would do it.