To help clear up some stuff.
The lumps have been proven to make more power.
So do valve enlargements and larger cams.
A 292 engine with stock cam and head was ran, then was tested again with only a lump added. Basically no change in power was recorded.
Once a larger valve was used, the power went up.

Another test was done with the 1.94 valved head to remove the lump. The power went down. This confirmed the lump really does add power with larger valves.

All the 250 and 292 Dyno tests were performed by me.

Here is a page from my website that shows some dyno runs performed on the 292.
http://www.12bolt.com/65279inline-cylinder-head-flow65279.html

Inliner Member 1716
65 Chevelle Wagon and 41 Hudson Pickup
Information and parts www.12bolt.com