The ratios arent totally nice, but according to helmod they are pretty close (everything fully boosted) , with 2 refineries supporting approximately 4 light->solid, 3 PG->solid, 1 heavy cracking, and 7 rocket fuel. Since 2 plants can fit in the vertical space of a refinery, this allows for a pretty neat stackable layout:
![Image](https://forums.factorio.com/images/ext/e1667e4b2426ebfdb61adbc73f40c772.jpg)
Each set of 2 refineries converts 5.5k steam plus 1.1k coal into 107 rocket fuel per minute.
Steam is fed in lower right, water lower left. All solids are handled with bots, you could probably also use belts and use UG belts to cross the beacon line from solid to rocket fuel, but that might not be balances since the light fuel is boosted more than the PG fuel.