I'm having troubles finding setups. Link anyone?
There is really no need. Passively cooled BigReactors are actually rather simple to build: Build a box with reactor casing and glass. Put the cores in the middle. Surround with coolant. Top with reactor control rod blocks. Shove a controller, IO port and RF tap and your'e done.
How big a box? Decide on your ideal power output in RF/t - divide by 500 and that is the number of fuel rod blocks your design will need to incorporate.
A lot of the power produced in a big reactor is produced by radiation being absorbed by coolant, radiation travels no further than 4 blocks so you need to have 1 to 4 blocks of coolant between each rod and the edge of the reactor, depending on your available space. Cyrotheum has an absorption of 66% so each block of coolant past the first only yields half as much RF. (Ender has an absorption of 90%).
Once the reactor has produced enough cyanite, swithc to active cooling by building a turbine for a 10 fold power increase