Slip on mufflers for 4 into 1, 82 KZ750h

Got my 82' KZ750h home and I am starting to sort out what needs immediate repair or replacement. Issue I am running into is it came with a 4 into one left hand exhaust. I have no idea on the manufacturer, The muffler was a slip on (not welded in place) and was some crappy Screaming Eagle Harley pipe that I found out afterwards had the baffle ripped out. AKA it was a straight pipe. its a standard 1 3/4 diameter pipe from the header so most universal slips should fit.

So I want to keep the 4 into 1 exhaust and need to find a suitable slip on that would work well with the standard airbox and preferably standard jetting. Although if I have to rejet its not a problem.

1- Any suggestions?

2- How long should I be looking at for optimal running, I see them as short as 12" all the way to much longer?

3- Would something like these be okay ( I really like the styling)
17" Goose cut
15" slash cut

I have a 4-1 jerker for a kz750 if you'd like to buy it. Pm me.

Thanks but I am not looking for a new exhaust. I already have a 4 into 1 header that is in okay shape, need information on a good muffler to add to it.

I'd look into a muffler from a ZR7/ZR7S (2000-04 ZR750 F/H air cooled models). Not sure how easy it would be to mount on the left side, though, as it is a right side muffler. And just to be clear, left & right sitting on the motorcycle.