For temp. control I would use either a Honeywell chart recorder or a UDC3000 controller and RTD. Both of these will allow you to ramp up to temp, hold, and ramp down if needed. We used alot of these in a plant I worked in to control some ovens and steam dryers, in fact I have several UDC controlers and instruction books and maybe even an RTD. If you decide to go this way pm or e-mail me and we can talk about it. Marc is right on with the electrical requirements, you will need a circuit with more ampacity to carry your heaters. Also you will need 1 large (NEMA 2 or 3) contactor, or 2 smaller (NEMA 1) contactors to control the heat.
Life is tough, Life is tougher when you are stupid.