12lb injectors at about 50psi or 19lb at 30psi (mpg, preformance)?

I have a 1993 ford 4.9 300ci. Would (data in title) be better for gas milage, preformance, and reliability?

I'm thinking larger injectors because the engine doesn't have to waste energy forcing the gas through. I'm thinking- engine with clogged injectors has a lower mpg than clean injectors.

You're all over the map here but I can tell you one thing for sure, the engine doesn't have anything to do with forcing gas through the injectors, and if you're debating the benefit or disadvantage of fuel pressure in terms of fuel injection, higher pressure is better if your pump and ecm can support it. Higher pressure atomizes the fuel into finer droplets for better power and economy but most ecm's have current limiting in their injector drivers and excessive pressure can trigger it.