I preface with stating I have very good skill mechanically, Ive built and tuned plenty of motors over the years, but this one is just really not making sense. I purchased a 71 with a 454 and a 4-speed. It appears to have low gears, as I am doing 3000+ when going 65-70. The motor was rebuilt as a stroker motor topping out at 496CI. It does have a smallish cam (Comp 11-430-8, which is 224/224@.050" .566 lift), but it does have stock cast iron manifolds, 2 1/2 exhaust, and Magnaflow mufflers. It has Brodix heads, a Brodix intake, and an 850 Holley DP. Plugs look fine, and it has 200-210 compression, and the CR is 10.5:1. Ignition is stock distributor and coil and a Pertronix conversion kit. I've checked voltages to that and adj gap; it's fine.
In troubleshooting this, I took it out this morning after a while of not working on it. It's got some power, but going around a corner in first, I punched it, and it barely chirped the tires. I would expect it completely sideways until I left off - nope... Even with the small cam and small exhaust, I would expect this combo to be around 500HP and 550 torque, more than enough to nuke tires, which it can barely do. The only way to describe it is that it feels like it's in a 5000 lb Cadillac or I have the rear brakes on.

Some things Ive looked at and tried

• Bumped timing to 20 initial, 36 all in by 2800
• Verified throttle is opening all 4 barrels (I had to buy a new bracket and cable holder)
• Verified 12V at the pertronix, and re-shimmed the gap
• Re-adjust the valves to verify the roller rockers have the correct preload
• Measured compression (200-210)
• Floats look good on carbs
• Plugs look of maybe a tad rich. (I need to verify what jets and power Valve I assume whatever they came from Holley with new)

Just doesnt pull like other big blocks I had in Camaros, and they were only 396. A 496 feels like my stock 270 HP 350 in 71. Since I didn't build it, I cannot verify that the cam is installed correctly. A severely retarded cam could have these low-end torque symptoms, but the cranking compression wouldn't be 200+. The next thing I am looking into is getting a hotter coil and an MSD 6A, and getting that out of the way, as 200PSI is pretty high compression, and if ignition isn't up to it could cause issues.