CKArms billet shielded ambi. Had a cast safety break and take a nice chunk of skin off my thumb. Won’t do cast again! The CKArms part was very easy to fit.
The barrel may be more of a limiting factor than the mags. One of the truncated cone bullets that I used had to be loaded really short until I had the barrel reamed. Be sure to check that along with the mags.
A course in any USPSA match cannot require you so start with gun in weak hand. If you choose to do so, that is your option.
Not using a HF, but Seekins and the push button safeties have served me well.
I use a thumb rest as an index point. The new CKARMS scope mount with integral, adjustable rest, fills the bill nicely. I have mine pretty far forward and the angle is pretty flat.