I have written about this before, but about 12-13 years ago I bought a new Taurus Model 63, a very good knockoff of the Winchester Model 63, which I improved greatly by refinishing the stock. Its receiver also had no provision for a scope mount, which I added so I could use a red dot sight. It's a well-made .22 and reliable as it functions well with every brand of LR ammo I have tried in it. A shame it is no longer made. The last one I saw at a gun show had a $600 price tag on it.
I bought the Taurus because when I was a kid I wanted a Model 63. I had a friend who owned one which I always coveted - it was so Winchester-ry. Back then I had to settle for a Remington 550-1, which was a somewhat less expensive option, but in retrospect was probably just as good as a Winchester 63, maybe better. I have one of those also.
"There scope mount holes are not factory and may be for an Echo mount."
I am no expert on Echo mounts, but the only ones I have seen have been side mounts, and on center fire bolt action rifles. Not to say that Echo mounts of a different design for the Winchester 63 weren't made. With such a flat-side receiver, it's a little surprising the original owner did not have a scope side mount installed, as it would have been much simpler to locate and drill the screw holes.