750 is too small.I use a 950 on a small block.
the 73 corvette surprisingly hooks fairly well. The muncie wont like all that torque.
you should work out your CR? The oval iron heads need porting,the 265 aluminum AFRs would be nice, or if you step up the cam then 335 dart square ports are nice. The biggest exhaust that fits under that car is only 3 inch,side pipes will kill your ear(s)