292/508 question

If you don't have a true 10.5:1, advance it more as long as you have clearance....

I install those in stock 340's at 100-101 range.

I think you'll be disappointed. I've swapped those for people, going from a 284 to the 292. The 284 outperformed or was equal to a 292 except for about the last 500 of RPM range.
Listen to C.B.... He knows his sh"t ... Had a few conversations with him.....