The return regulator at the rear supplying 7psi all the way up front doesn't sound like a good idea to me. I run a Mallory 250GPH pump set at 16psi, returning to the cell from just in front of the motor through a Mallory 4307 return type regulator with boost / vacuum sensing port. Really a cool idea using vacuum to pull fuel psi down at idle when vacuum is high, and when you go WFO vacuum falls, the port allows the regulator to jump up to 9.5 psi for the whole pass, then when the throttle is closed and vacuum rises,, back to 7psi,, in theory anyways. EVEN AT THAT, I am down to only 2 and 3psi of fuel pressure for the first 2 - 3 seconds of the run. Fuel is HEAVY and wants to stay at the starting line when the truck launches. The larger the lines you use, the more fuel in them, the heavier it is, the more pressure drop you'll see. You will have a serious drop in fuel PSI at launch, and having your pressure regulator all the way at the back,, seems to me like it is going to compound that problem. I'd put full high pressure all the way to the front, then regulate it just at the carb. It makes for a bunch of extra hose, fittings, and cost, but it's the right way to do it.
One of the best sites I've found to assist in fuel system design is Century Performance. Sam Solace has put topgether a really informative page on fuel systems.
Here's a link to Sam's fuelish tendencies page
oh, and here's what kind of a plumbing mess your geting yourself into. This is the regulator mounted onthe front motor plate of my Nova. Not a very good shot but you get the idea.
http://www.small-block-chevy.com/novam19.JPG