I take my 406 up to 5500-5700 every once and a while but it peaks in power long before. It handles it just fine but I have good quality fresh lifters. SBC stock bottom ends are pretty stout, I have heard from experienced race guys that they can take 7,000RPMS with good bolts, splayed caps, and a valve train that can take it. When I had the local dyno shop dyno my 406 they had mine wound up to 5,400RPM's. THey had a 68' camaro there with a stock bottom end 327, alum heads and said they were feeding it a 300HP shot of nitrous at 7K no prob. /forums/images/graemlins/yikes.gif