"Block relief" - L.M. Williams book

[Bob Culver]

The Williams book was written when Sevens were cheap and expendable. Many cars were everyday transport and  young owners were desperate for power to keep reasonable pace with traffic. Preservation of the original was not a factor.
Diagrams and considerable else in Wiliams are dubious. The camshaft exactly as diagram duplicated could not operate, and is way through hardening. 
The sv Ford V8 had tilted valves so the chamber had to be formed part in the block.
With revs,  rods bored different, gaskets, disasters, pistons can rise further than normal.