4.250 crank factory 340 block

My street/strip 408 was close to the 600hp range, I ran it for six years before pulling it to freshen. It showed signs of block flex in the main and cam bearings, IMHO a girdle would not help. Also four bolt mains in a stock block will not help block flex either, cap walk, maybe. I'd save my pennies for a good block, my ¢02.