Holley 450 w/600 baseplate

[DART66GT]

I'd like to try running my holley 450 on my stock 318. The baseplate has damage and the wrong linkage. I have a baseplate off a 600 with universal linkage thats in perfect shape. Could I use it? The 450 is an old Ford unit with no ports on the plate. The 600 plate has a vacuum port and pcv tube. Also the 450 has the old bowl with the vent on top Could I switch to the newer style without?

 

[DART66GT]

The only difference I see between the 2 plates (besides the throttle size) is the hole in the center of the plate. The 450's hole is almost 5/16 and the hole in the 600's plate has a brass restrictor the size of a small holley jet. Can anyone tell me what this hole is for?

 

[moper]

I tried that a bunch of years ago with two performance Holleys. I learned I dont work for Holley..and there's a good reason why...lol. I dont think I'd touch them...