I'm at 10.8 as well. Unlike others, mine is on the edge of detonation, and my intake valve probably closes later than yours. I run 22 initial and 35 total, and 93 octane. The car is heavy, tight converter, and tall gear.

What is your cranking pressure, and what do you call straight up on your cam install?

The Champion 12s are way too hot IMO. I run the NGK 7s all the time on mine w/o a fouling issue. Make sure that you have good fuel pressure at the carb under WOT as well.

My 496 ran best with 34 degrees total. I went the other way; I gave up compression for timing and I have no regrets. My compression is 9.7/1. The engine made 640 torque and 567 hp. It will do this all day long and run on regular unleaded to boot. I don't remember the figures but there was a big difference between 31 total and 34.

I had the motor apart 2 months ago to address an oil control issue. Before the teardown I looked everywhere for the cause of oil loss... Valley pan, oil pan, timing cover, valve stem seals....AND i did a dry compression check. The highest cylinder was around 190 and the lowest was 179. While the motor was out, I had the block honed and douched out, then file fitted new rings and screwed it all back together. It runs cleaner with no smoke and certainly makes more power than before I pulled it.
I have always used these Champion plugs and ALWAYS had to limit my ignition timing. It WILL be interesting to see if the colder plugs help. I'm going to install some NGKs today.

I've been to three auto parts stores and NONE of them know what an NGK 6 spark plug is. I had each guy try to cross-reference a RC12YC to an NGK, and still no luck. What is the EXACT NGK part number that I should be looking for? NGK FR6?

The NGK number for stock heads is R5670-X with the X being whatever heat range you want. 5 being hottest.

Dont know what heads you are using, maybe they take the same plug??

BCPR6EP-11

Wild R/T: Is that a plug spec'd to fit an Edelbrock head?

Thanks wild man!

Man, these plugs aren't the easiest things to find.
You go "off the reservation" a little ways and things get murky. I went to 4 different auto parts stores and only ONE was able to help. I wanted NGK plugs, but for some reason, most of the computer systems are set up for part numbers for OEM applications. Deviate from there a little and the parts guy gets lost.
When I worked in Auto parts retail, there was ONLY the spark plug number. You need a RC12YC ? Look on the shelf. Now that number is joined by a "stocking" number. If there isnt an OEM app for that plug, finding the stocking number is very difficult. One guy at an O'Rielly took the time to email Champion to get info on the RC10YC that I wanted. NGK? unless these stores had them on the shelves, they said they weren't able to order them. I can't understand why. I ended up buying some RC9YC plugs only because they are an ON SHELF plug and readily available. I dont race much, and at least 80% of my driving is at half throttle or less. I'm sure that these will foul quicker than the 12 series, but without camping outside the Champion factory, its all I can do.
Thanks for the help.

http://www.summitracing.com/parts/NGK-6779/

At your door in like 2 days. You won't find these plugs in stores, gotta use outside sources my friend.

These are the ones I use. Come with a slightly wider gap out of the box, .040 or so.

I've bought plenty of things from Summit over the years, but I never considered them for spark plugs. Thanks... GREAT tip!

You may want to look very closely at thtat carb's metering blocks. I've found them running very lean because of aluminum "hangers" where the drills broek thru but the shard was left attached. I found three of them in one carb... Also, FR6 are a great plug and are close to the Champion heat range 9. I get them at my local Car Quest.

It should be zero deck with that combination, as others have said try the colder plug if no good I would certainly consider that comp cam you have.