The original Brutus build is not electric, but natural gas, so that may in fact be a good place to start, especially for seeing how the flame control works (temp controller + pilot and valve.) The write-ups are very good and many have successfully built clones. A new spring is needed on the honeywell valves to convert from natural gas to propane - this blog describes the process.
There are a couple of others pages with propane builds:
2-vessel gas fired HERMS build
This one is nice and simple - just one pump and doesn't require any kind of pilot or valve on the propane burner since the mash is done in a cooler.
Single tier HERMS build
This is a single tier system, like the Brutus/Electric Brewery, using PIDs and a honeywell valve to control the flame.