You will probably need to get those exact model mufflers - the 83 750 was a Unitrack model, and had different rear mount points than any of the previous twin-shock 750's.
If you were happy to modify a set of 4-2 stock pipes (just at the rear mounting points), then you could possibly use a stock set from a number of early 80's 750s - the early ones are a chrome finish, but I am pretty sure the GT750 (shaft) models were that black-chrome finish used on the GPz750. All the exhaust port spacings and port diameters are the same, so they are all interchangeable (at least at the front).
Good luck - personally I reckon you should fit a nice 4-1 chrome system - they look heaps better !
