Edelbrock heads with OEM manifolds

Jim Kueneman said

9.5:1 on the Aluminum head cars. Had 8:5:1 on my stock steel head 318. All run plates to allow 18 degrees idle and 30 all in. Cams are all low duration hitting around 7.5 dynamic and 185 PSI cranking (the cast head build was lower) My car with the stock cast heads and low compression pinged like a bugger and struggled with over heating in traffic. Both the aluminum head 318 and 360 have never pinged and run cool. All radiators are 4 core done by GlenRay.

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I've also had similar experience, the 5.9/360 in my Duster has ported Edelbrocks and 9:1 compression while the 360 in my D200 has stock iron heads and 8:1 compression (rated 8.2:1 but likely lower). I've never had the Duster engine ping even when the ignition timing was overly advanced but the truck engine pings like a SOB especially in hot weather if it has just a little bit too much advance.

To add to the OP's original question, I've had issues with an early 340 driver side manifold interfering with a factory Magnum head in that same location as the Edelbrocks.