Well I got one for you.
Both times I put X-heads on LC 318s, with the 340 cams, I lost a ton of torque down low(sub 2400ish). Sure it made more on top. Sure I had passing power. Sure it was a dog below 2400ish. Sure the cure woulda been a higher stall converter and more gear.
The point is it lost torque down low.When the Dcr falls into the basement, so does drive-ability. You are then married to stall, gears , or a diet. Woulda been cheaper to fix the compression right from the get-go. JMHO.