What was the first year that USAC allowed 410 engines to compete in the sprint cars? Did they go from 305 to 410 in one year or...? Anybody know?

i dont have specifics but i believe they went to 358 in 80 or 81 and 410 3 or 4 years later.
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Thanks for that. Do you know when they started to allow aluminum blocks? Or did they do that when they went to 410?