Not sure how that's wired... you'll either just need to run that off of an ACC or IGN circuit or you'll need another relay between the two.
The black wire with the orange stripe which runs to the igniter and coil packs and injector resistor pack will work; So would the blue wire with black stripe which runs from the circuit opening relay to the fuel pump relay... Or, the Black wire with the red stripe coming off of the Main EFI Relay... Or, I previously thought that the +B pin in the diagnostic box was always powered but looking at the diagram I may have been mistaken; If it is switched you could use that line too or the FP line running to the diagnostic box too (both black with red stripe).
Make sure you're not exceeding what they state as the maximum. Ideally you'll want to be 20+% under the limit during normal operation. It's easy to accommodate higher power devices though by just using their circuit to trigger two other relays (one dedicated to each fan).
How are you going to mount that thermostat?
Here's another one worth considering too:
http://www.summitracing.com/parts/SUM-890015/ You'll have to open up one of the ports used by one of the A/C sensors (which you aren't using anyway) but it's rated for a little more power and preset for a good temp range.
Here's the instruction sheet:
http://static.summitracing.com/globa...20890016-a.pdf