The Performer RPM gets the credit as the first do it all dual plane but the Edelbrock LD340 from the 1970s is STILL a fantastic manifold. The factory iron intake on the 1970 Chevy LT-1 350 is a high performance dual plane as well.
My 70-1/2 LT1 Camero Z28 had a factory aluminum intake (370 hp)
