Here are two old discussions that touched on this topic. You might want to search this forum for all discussions on "fenton". Such a search does not take very long on the new server.
http://66.221.101.248/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=2;t=003101#000000
http://66.221.101.248/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=2;t=003003#000000
Water heating is my preference, if you are using an intake manifold with passage(s) for water (like an Offenhauser or Clifford intake). However, if you are using the stock intake manifold, a connection from the Fenton headers is fine.
If you heat with water, you should use a thermostat and take the water from below the thermostat (the engine side, obviously, heats up faster - actually quite quickly). You could use the thermostat housing plate from Tom Langdon (mentioned above) for the supply of water and put a T in the water heater hose that enters the return side of the water pump. You could also take the water supply from a T in the heater hose connected to the lower thermostat housing.
Tom Langdon also sells a plate and fittings for the bottom of the intake (at a much lower price than the ones sold on eBay a few months ago).
My 1960 261 engine has extra ports for supply and return of water (both on the "wrong" side of the engine but they can be made to work). Another option for supply of water is to use a GMC truck's thermostat housing (I understand it has a port on the intake side of the lower part of the housing).
Good luck.
Tim
