I switched out the Holley today, and installed an Edelbrock. I made two thick (aobut 3/8") rubber washers by cutting "cookies" from heavy duty oil-cooler hose. Put locktite on the bolts and clamped it down pretty tight. Edlebrock also uses a very thick rubber shim inside the clamp, so it's pretty isolated. Can't hardly hear it run.

It probably would have been cheaper to run a Delco, but, a) I didn't think of it, and b) the Edelbrock needed no re-plumbing.