FYI - here is one where there is a specific pitch on the website for use in air cooled Porsche engines. FWIW this product was recommended by a Porsche shop about 40 miles from Philly when the local PCA club held a meeting at the shop. I've been drinking the Brad Penn koolaid...so no direct experience with Joe Gibbs.
https://lnengineering.com/joe-gibbs-racing-dt50-full-synthetic-15w50-aircooled-engine-oil-12-quarts.html