Holley makes a 450 Vac sec with the ford linkage and elect choke.
I dont know why a 600 is such a mainstream number. imo its too big for most situations with folks who are running mostley stock parts.
MFGs should make more 450 and 500's
Back in the early 90's I had a Holley 600 Vac sec (#80457) on mine and it ran like a bat out of hell but......
I was fouling plugs like crazy.
in the late 90's I went back to my old faithful 2100 which I had Pony rebuilt for me and although she dont run like a bat out of hell anymore the maitenence is a lot less and she fires up every time. lol
1970 Mach 1 San Jose built Dec 23 1969. Marti says 1 of 7. Purchased in 1987. Original family owner of the powertrain 351C 2v FMX.
1993 GT 11,000 miles, Built 2-12-93 Auto, 3:27 Axle, cloth, sunroof. Untouched except for rubber and battery, Purchased new 8-3-93. still has the factory windshield fluid and new car smell.