Hey NNorton, I still run 670s on my 400, (built years ago). It may not help you much because I went the opposite direction using TRWs replacement for stock flat top pistons (.030 over) and running 1 oz of octane booster per 1.5 gallons of regular fuel. I only drive the car about once a month so am willing to pay the price in fuel to enjoy the throttle response etc. of the way we ran them in the 70s! The cam as I recall has an adv lift of 458 and adv duration of 292. The lobe sep is 112 . A mild cam, has a nice medium lope, tons of low end and still wants to pull pushing 6K.
I know you all will say I'm crazy running 10:75+ to 1 compression, but this little car is "funner" than ##it to drive!
Don't we all love the power of a pontiac!