"...Crower nuts are a lot lower price than Mr, Gasket, etc, ($38 vs $64).
Is there any reason not to use the Crower ones?..."
Haven't read any bad reviews of the cheap Chinese poly-locks. Back in the old days I used Mr. G. But nowadays, there are lots of brands cheaper than Mr. G.
CC has some cheap ones.
https://www.summitracing.com/parts/c...RoCOowQAvD_BwE
http://www.jegs.com/i/Comp-Cams/249/...RoC_OsQAvD_BwE
https://www.ebay.com/itm/COMP-CAMS-4...4383.l4275.c10