I recommend using the best retainer and keepers you can get for any motor that will be revved up beyond 5000 RPM up work
I use a lot of Comp Cams 10 degree tool steel retainers on my street and strip builds now, 10 degree Titianium (SP?) on race motors that will see over 7000 RPM regularly up

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)