Anyone know where I can find one or a suitable replacement?

The Air Venturi is about the closest pistol that is currently available new, that I could find.  Pyramid Air is probably your best choice, though you can try some of the other on-line airgun stores.

E-bay, and gun broker may have auctions for the 747.  Gateway to Airguns classifieds may produce some options as well.

I'm sure there were at least ten 717s built for every 747.
717/747/777 were identical except:
747 added a Lothar Walther choked barrel (and a hair less velocity because of the choked muzzle) and a sort of adjustable trigger.
747 added wood grips and much nicer metal sights to the 747.

So one option would be to get a 717 and perform the Don Nygord mods to it.

My 717 has a roughly 4oz trigger with essentially zero travel. But I have extra sear/hammer parts that I bought from Daisy when they were available 20 years ago and it's not the end of the world if the sear wears out in 5000 shots.

If CO2 is acceptable, older stuff like Crosman 111 / MKII and S&W 79G would be good for beginning 10M work and weigh a lot less than a 717. The 111 trigger leaves a lot to be desired however. One of the best offhand groups I ever shot in my life was the day I got my 79G. Four inside the X ring, with a called flyer that was just barely a 10.