Header flanges or shorter spark plugs to gain space on 383 with Edelbrock 5090 heads

[wasco]

I'm looking for a set of 3/8" thick flanges for my 383 with headers and Edelbrock 5090 heads to try to get a little more clearance for spark plug wires. I just got a new set of MSD wires with the bendable boots and before installing I want to make sure they have all the room they need. I also have a set of those boot sock shield things. I've read the Autolite AR3933 is a shorter version of the RC12YC plug, but online sites show the Champion is 3.32 and the Autolite is 3.38. Their temp ranges are WAY different, too - according to sparkplugs.com, the Autolite is 3 and the Champion is 12? Does anyone have suggestions for a shorter plug or should I stick with the recommended Champions and hope the flanges work? Thanks!

 

[33 IMP]

I'd saw away most of the flanges, and split them. I split all the flanges on my headers.
When each cylinder is independent of the others, the flanges don't need to be excessively thick.

 

[dvw]

You could stack a couple of copper gaskets will shim them out. I've not had any plug wire issues using box headers with Edelbrock heads. Run several sets. Accel makes a short plug.
Doug