Sounds just like my first 440. Don't bother with anything less than the l2355 piston. I bought the l2266f and they were way down in the hole like stockers I ended up decking the block square then milling .050 off the 452 heads with steel shim gasket. I have had the 6400 and 6401 cam in that engine, it's a dog with the 6401 down low, but picks up later. I run the motor on 87 octane all the time, I just couldn't go too crazy with advance curve, it likes the middle weight springs and I took the plugs colder because it use to run on with the key off.
With the amount of head choices out there now, I don't think I would ever bother with stock heads ever again unless you're super tight on budget. I regret all the time and money I spent on my 452's.
The engine made the most power with a big thermoquad on it and lost power when I switched to a 750 edelbrock, it would pull vacuum at wot throttle with the edelbrock.