Sorry Marty, I've had a brain fart, I thought you were refering to the Nascar P8 heads that go on the R6 Block. They have a 4.5" Bore spacing. As far as I can tell they bolt up to the R4 blocks, Brett Miller had a pair as seen here:
https://board.moparts.org/ubbthreads/ubbthreads.php/topics/1418930/p9-mopar-head.html

Last edited by LA360; 06/08/16 02:37 AM.

Alan Jones