Ron,
save your money, the steel caps aren't needed, this ain't no small block Chevy!! lol..... Cleveland caps are good beefy pieces in their own right. I've never known a Cleveland to break a main bearing cap, they always crack in the bulkheads or open up holes in a cylinder wall. If you were drag racing, dumping the clutch at 8000+ rpm, as long as the motor is naturally aspirated I'd still say it isn't necessary, for sports car driving the stock caps are plenty.
You bought your Webers, cool!!!
I have no idea where to find a NASCAR block. I would start by asking around some of the Cleveland engine specialists, like Mark McKeown, Dan Hebert, etc. If somebody owns one, they'll probably want a good sum of money for it, you may want to consider giving SJ Performance of Australia a phone call & ask when their new alloy block will be ready for delivery. It will be a pretty costly piece too, I was told $5K USD last spring, that may have gone up since then, you know how early pricing tends to do that.
Good luck my friend.
George
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