Call Summit Racing, they have everything for mild to wild engines. Do not get sucked into bigger is better. You need no more than 40 to 60 GPH (gallons per hour)
I run my three carbed, 331 with a single "el cheapo" Purolator electric pump ( 30 gal/hr) which is about three years old now. Never starved it, never misses a beat. Keep your mech pump. If it's not big enough, you'll only know it when you try to top the vehicle in.