I remember an article by Cecil Yother (maker of leak down testers, torque plates etc.) saying a limited slip differential was quicker than a spool in his high 10 second 70 cuda.

I don't recall many other details from that article except that it was flat top piston, iron head 440, auto trans. I'm not even sure what tire size, but I think it was leaf spring equipped ....I wish I could find the article.