[RICK LAKE]

Dimis Problems are starting to show with gas here in the states. The 10-15% methonal is eating any rubber lines that are not designed to handle this kind of fuel. Over time the rubber is falling apart into small partials that are getting through 20 micro filters. Either plastic or Stainless lines are going to be the only way to go down the road.
Build your fuel system so you can expand without alot of changing the lines. Run your carb setup but leave it simple to just add a short line with added filter and one way valve and cap the line. Also run the relay and wiring for the electric pump. This way all you have to do is connect. You can always go back to a carb if needed.
In tank fuel pumps need gas to help cool them and extend their lifes, I run 1/4 tank min with 2 sets of baffles in the tank. I did have to remove the foam because it was breaking down. Tank foam was only 5 years old. May have been due to gas additives and boosters. Now run only 91 without and additives, even at track. Have added 2 gallons of 100 unleaded couple of times and found no change.
Walbro fuel pump(255) will push 80 psi if needed. Running #10 and #6 lines will give you an 700-900HP range. This should cover all your needs. As for injector duty cycles, going small will cause the driver to hold the injector open longer, make more heat to both, and over time burn out the system. You can make the injector run at a higher pressure but will cause failure of the pintle seat and cause a leak from fuel wash wearing out the seat.
A set of 45-60 pound injectors will be in the ball park for your setups. Dropping fuel pressure also drops flow to motor and makes a larger injector smaller, same applies the other way. This setup is for 8 injectors, 1 for each cylinder. A throttle body system would need 96 pounds for running a 452 or 482 and would ned to watch the A/F ratios in the 5,500 rpms and up for a lean out condition. You are looking for a 12.5-12.7 on accell and 13.2-13.5 on cruise for safe ratios. Can go leaner if needed, depends on weather around you. Good luck. Rick L.