Before you look for plans, ask yourself what you will be using the structure for. I have built similar footprints in many ways. If interior posts will be in the way, consider a truss; if not things could be easier (or not). Consider too, what logs you have and what they can yield. If you cannot mill either 24' or 36' timber, this will effect your design. If you can, same said. Orientation will also play a role in your design. Is the ridge running 24' or the 36' direction? What is your desired eave wall height, pitch, and ridge height?
Generic plans might help you build a structure, but will it be the structure you want? At the turn of the century, there were several plan books published by Radford, Louden, and others. A google search might turn something up.
