600 vs 750 Holley

I have had 600, 670, 725 and 750 vacuum secondary carbs on my 360.

The throttle response and mid range performance with the 600 and 670 is far superior to the 725 Demon or the 3310 750. The 725 and 750 had a slight top end (above 4500 rpm) over the 600 but no advantage over the 670. The 600 and 670 get about 5mpg more than the 725 or 750.

If you have the 750 go ahead and give it a try but if your car is primarily a street car I bet you will be putting the 600 back on. FWIW, my Barracuda has run a best of 13.7 @ 102 mph in the 1/4 with a very traction limited 2.2 sec 60'. The 102 trap speed should push the car very close to the 12's if the traction issues were sorted out.

BTW, comparing a square bore Holley to a Spreadbore Thermoquad is an apple and oranges comparison. The Thermoquad has primary bores that are smaller even than the 600 and the secondaries are never fully utilized in a stock or near stock small block.