GK 115T speaker recommendation

Hi there!

A friend gave me a GK 115T with a non-original and dead anyway speaker for free. Now I'm looking for a good speaker that would fit this cab. Of course I used the search function and found this one here:

Speaker gurus- equivalent replacement driver in cab?

If you read through this thread, my main concern is the part with the ports being tuned too high. I really don't have that much experience when it comes to bass cabs, so i wonder what the results would be if i just close the ports and make it a closed cab. Do i have to watch out for something specific? Could i use whatever speaker or do i need to take care of what i use? Essentially speaking, i really have no idea what i should do with the cab to get the best out of it. I see it as kind of a project, so messin around with it to get good results shoudn't be the problem, but i'd still need some advice on how to do it.

I also want to build a B15 clone, and then the question would be if i could make this cab a perfect partner for this amp.

i hope someone can lighten me up a bit on how far i can go with this cab, and most of all, how much does really make sense? right now it's sitting empty in my garage, and i want to change that asap.

thanks a lot in advance!!