I copied your idea but I did the Aug24 78.5 79 strangle. Sold at 6.1 It's now marked about 3.5 vs 76.55 (45 vol).
I think it benefited you have downside strikes that you could slide into.
I also sold the 72.5 85 strangle and that is looking better ($1.95 and it's marked at 43 cents).
Good find.