At the time of these blocks I believe only European F-1 racing had bigger racing budgets.
Guy told me about a chassis he built and used x-ray thickness gauges and careful sanding a grinding to get it within hundredths of the Nascar minimum tubing diameter. Got the tubing manufacture to make special dies to get the thickness closer to start too. Brought the chassis down 200 lbs. ... was for a "man in black" ;)