A while ago I sold a fat WS6 front bar that came off an '81 Trans am. The buyer claimed he had read on the 'net that it could be easily installed on Chevelles so he bought it for his Chevelle. I think his car was a '68 or '69. Might be worth looking into as they might be somewhat easier to find and also benefit your cars handling.
I do not know if the buyer was successful though, I just remember what he said when he bought it from me.
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Actually, in real racing ... it IS how fast you went.