hmmm dificult question this...
in terms of actual stress them its likely the RST block will have had a fair bit more.. will this of weekened the block.. not really...
The thing is all CVH blocks were the 'same' apart from the oil feed and the CPS etc.
The MAJOR thing to look out for is the actual casting of the block.. some CVH blocks have HORIFFICALLY thin bore walls as it is! you wouldnt want the be pumping 25+Psi and over 250 horses thru a block like that i tell thee.
Best thing IMO is to get someone to check the block over and say if it is suitable for the application... any tuner you trust would be able to do this..
i would take it to Karl personally. will at least put your mind at rest when you hammer your foot down and see the boost gauge go off the dial!