Use what you have available, unless your buying a new reel anyway.
I own several and on the sawn-off 6' use a small 3000 size. On the 9' a 4000, really not rocket science.
The small size Daiwa 2600 size I think it's a 1600 looks ideal. But any 3000 to 4000 would fit the rod.
Even though the rods can cast a long way, most people are buying them for short range up to 60 yards or so, so why would you want a big reel for that. If you buy a scope for long range, in my humble view it's a mistake. A 12' would do a better job for all the obvious reasons. I use mine for stalking and that's all.