7.3L - maybe try one of those twisting garden hose nozzles. (Sorry dry sense of humor that I sometimes can't restrain.)
The first thing I would consider is the how much pressure and flow potential an application this size would require - then plan on a system that will have a potential at least 10% more than your requirements. From there identify the appropriate pump, pressure accumlator and routing hardware you are going to use. Lastly you can start to look for nozzles that will deliver the spec'd flow you are seeking at the pressures that your selected pump can generate.
Generally DIY sets use nozzles for oil burners if they forgo Aquamist's spec specific jets. Most will generate the desired fine spray at the pressures your pump would generate and there is a wide variety of flow rates available. Keep in mind that some of the higher flow rate nozzles may not produce as fine a mist as needed. To the extent possible consider multiple lower flow rate nozzles that will generate finer mists.
I have never used their products and can not speak to their desirability for this application but here is one example -
http://spray.com/ and a google search on oil burner nozzles -
http://www.google.com/search?sourcei...+burner+nozzle