As some scary Slant 6 motors have shown, 4 mains isn't automatically a low-speed engine.
Based on a GMC rod, light piston, and SFI-quality damper, 7,000 RPM is about 113,000 f/s/s, a very conservative figure for a race engine (lower stress than a SBC 350 with 5.7" rod at 7,377 due to lower piston weight).
The mean piston velocity is 4,594 - not good, but possible with a quality forging.
The RPM will require a steel cam for the spring pressure, and probably a fabricated rocker arm or welding and doubling to stiffen the original (which may turn out to be Buick L8 or GMC?).
