not a 396 just a 323:(

You have no low end because the parts are mismatched. Was the blocked decked heavilly? Did you use the MP thin head gaskets? Were the heads simply milled to clean up the gasket surface or milled to lower the chamber size? Because otherwise the pistons are not at zero deck, the stock type gaskets are thick, and the head's chambers are around 62ccs. That means your true static compression is close to 8.9:1, or low. Add to that the cam which is too large for the gearing you have, probably need to be degreed to be even close to where MP wanted it, never mind what you might want to run it at, the intake with 340/360 sized ports, the carb that is the dry-flow equivolent of a 750cfm Holley, the heavier and harder to spin 727 with a huge convertor, and no gear. If it were me, I'd take a couple cylinder pressures and see where you're at. If it's lower than 140psi you have issues requiring more changes. For a quick fix, swap the carb for a 570 or the oldschool 600 Holley and advance the initial timing and curve as far as you can. For a longer term fix, if you want to keep the gearing, I would plan to swap in a 904 (has a lower 1st gear, weighs 40lbs less, and takes 20 less hp to drive) with a tight 10" convertor with a stall no higher than 2400, replace the intake with a Performer 318/360, replace the carb with the 570, and recam with something more modern that will work in the power band the gears put you in. I'd imagine it's currently like driving a wet sponge until it hits like 4K rpm.