Whats Wrong Combo

The convertor is not holding the engine. Meanign the stall is off, and it's way inefficient in high gear. Talk to Lenny at Ultimate Convertor Concepts. PTC is also good. You will want a special unit to make the flash stall you need with the street manners. Teh heads may be a mess W5s are known for a few quircks. Like core shift, porosity, and typical Mopar quality machine work. So it is very likely they are a limimt on power. To be honest, I would have a head flowed first, to see what the thing can get for air. Then see if it's makign the power it should. WIth the rigth head package, I would expect you to be in the 530-550hp range. Maybe not 10.0s, but with the right race oriented package, high tens is doable. I'm also skeptical of Demons, but an 830 Holley is equal to a 750 Demon because of how they are rated. So that 870 Demon is a bit bigger. I would be looking to port the heads, do a little intake work, add a 1" open spacer, and get a 950cfm Race Holley or larger. You have to know what the heads will support before you know what you're missing. Post results of leakdown too.