Here is a different approach to guitar straps for your perusal that is a balanced delight to use!
Fifty years in use, no alterations to my vintage Martin D's, no guessing the wrong drill size, no drilling holes, no expensive ugly chrome hardware to purchase, no dangling flower child mounting ribbons or strings!
Be advised first, although REAL leather can be found, most leather on the market today including pre-made guitar straps and belts are of "manmade" leather. If you look closely you will see no "grain" to be apparent as is expected with real leather. Manmade leather fabrication is akin to sausage making. The resulting "leather" is stiff and cheap looking without proper surface patina or grain.
These straps (the tooled or embossed kind) you will find to be very uncomfortably stiff and unmanageable. Most are expensive too.
A good source for real leather strapping is a high end horse tack shoppe. My choice is halter driving mains of 60 plus inches.
The only attachment of the strap to my Martin D is the end-pin. One pin, many guitars. The end-pin tightly and permanently pierces the continuous mobus loop strap in one place only. It is installed and removed from the guitar via the end-pin at each use. (for some 50 years now without a problem)
One strap, one end-pin, many Guitars, no problem.
The strap itself is one circular endless loop (around my neck and the body of the guitar) with end-pin permanently attached which I wear over my shoulder in the normal fashion even without the guitar being attached.
The guitar body only, is hung within the leather loop, as it rounds the neck heel it suspends the body forming a perfect balance easily allowing neck attitude adjustment while playing. Very comfortable and safe.
When performing, after the last song, I simply pull the endpin with strap attached freeing the guitar from its harness. The strap remains over my shoulder.
This is a perfect arrangement for vintage instruments as no holes need be drilled and no neck stress is applied as there is with head stock mounting methods.
Try it you'll like it! Mountain Tyme