IMO if you want to tune your carb best install an O2 sensor. Then install a gage and you can readily see the difference at any throttle level without pulling spark plugs. Then later should you feel the need for EFI you already have the sensor!

Digital Air/fuel Gauge, Part # SUM-G2986 $27.95
O2 Sensor, Part # SUM-G2989 $29.95
Weld-in BUNG for O2 Sensor, Part # SUM-G2990 $4.49

I also agree the Holley D/P would be much better suited to that motor.

Kitz