340 carb size

I would think that the carb you have should be good. You may have some other problems as 'dodge freak' said. I've got .504 lift cam and 750 cfm is the 'recomended' carb. Your .497 lift shouldn't make that much of a difference.

Thre's always a simple answer to these problems. The forest tends to get in the way of the trees, and I HATE it when the answer can't be seen!!!

BTW....NZ KICKS ***. I used to stage out of Christchurch when I ran supply runs to McMurdo Station, Antartica