Hi Phil.
Just read the chapter for the first time in years, i just cringe at some of the things i did then!!
The basic problem with the chevy block, even the 010 high nickel version was that it just was not strong enough. the first iron block had gone past its safe run number and at least it ran the record before giving up.
the second iron block was brand new with billet main caps etc and it should have lasted longer. i think we were just unlucky with a badly cast block which just fell apart- if you look at the pics you can see the difference.I dont think the weight of the cars made any difference.
When steve rose and me sat down and planned the Plan X slingshot the first line said new Donovan ally small-block for obvious reasons. the second line said No more used parts and budget decimating paintjobs. we both agreed if plain black was ok for garlits and hall it will do for us!! With the ally block the previous block problems disappeared and we ran a best of 6.85 and 6.94 at Blackbushe. Built a new rear - engined car for top alky and ran from 89 to 93 with the same motor with no block problems at all with a best of 6.56 / 207. it ran 6.6s like a bracket car! I still have that block No 0147 and it will shortly be running again with all the nice new parts fitted.
So in conclusion i will say that any of the aftermarket blocks ally or steel available today would get the job done- I have a new Dart ally block here for another project- what a great piece of engineering- i wish it would have been avalable in 1980.
Norm.