[Theodore R.]

Do we ever see low information voters turn out in large numbers to vote in a Republican primary run-off election?

I can't think of one. Maybe the 1980 U.S. Senate runoff in AL, won by Jeremiah Denton, but I don't know if his voters were "low information". And I don't recall who Denton beat.

[Hoodat]

Not sure if Denton even had a primary opponent. The real action was on the Democrat side where challenger Jim Folsom defeated incumbent Senator Donald Stewart in the Dem primary. Denton went on to win in November becoming Alabama’s first GOP Senator in over a century.