Well, I made the switch, and I like it. My cam seemed to like it to. I had the pinion snubber mounts welded on today and installed the 410's. 275x60x15's seems to like a 410 over the 354's. I need to order the right count speedo drive pinion now. I was amazed how easy it was to swap gears.
Since I don't care about interstate driving, this swap was good for me. Lots of back road little towns to cruise to. Once I get back from working in canada, I'm installing some 2 inch x 3.5 hookers I have ready and let the engine breath a bit while I'm building the 318 for the car. I got to try and rebuild my 4 speed for the first time.
So by seat of the pants, you can definately tell the difference from 354 to 410 gears. I may have lost some top end, but can use all this in the 1/8 and 1/4 mile. Which is really what a muscle car was about back when they were built. I did keep my 354's tho. Only takes a couple hrs to swap them back in my set up