I'm setting up 2 4160 (450 CFM) mech. sec. Holley's on a tube tunnel ram, feeding a 540 cu.in. Cadillac. I had the same fuel volume concerns as you. I scrounged up a pair of used float bowels, and as soon as I can find the time, I'm gonna drill and tap the transfer tube holes for 1/8 inch NPT, and run fuel hose and a "T" fitting for a second feed point to the carb, between the front and rear bowels. I think this will work, but I haven't measured the boss sizes yet. It might over power the floats or upset the metering, I just don't know enough about holley's to know, so I'm just gonna try it. Any of you Holley guru's want to jump in here?????? tks Paul