Fuel piping question

I think 3 different members have replied and ask the same question, how much HP am I planning on having. The number that was given to me by the builder was somewhere around 475 - 525. I am using a set of 915 J heads with some porting and that will probably be a bottle neck for HP. One thing I didnt mention in my earlier post was that at some point I plan on running a 2X4 setup that I have so I dont want to run into any fuel issues. Im not sure at what point I will go that way as I will start with a customized 750 holley DP from SMI. So the reason I am thinking of larger lines is because of the 2X4 setup. With that said I contacted summit tech, they were the ones that gave me the suggestion to use what I originally posted and the tech I spoke to said he would change the first hose and instead run 2, 3/8 -8 AN lines from the sump to the filter, then run the 3/8 -8 AN to the pump and from there to the regulator run a 1/2" line as well as a 1/2" return. He assured me the pump will have no trouble keeping the 1/2" line full with pressure and volume. Then from the regulator to the carb or carbs running -6 AN. He also said there will be many different opinions and most of them would work fine with no problems. Thanks for everyones thoughts and opinions. Hopefully sometime this fall I will get this piped up and be able to fire the engine.
Rod