Your T-900 should be spliced using a core to core splice. In the videos, my partner Andrew shows his method which is pretty much like what you are looking at if you're looking at the New England Ropes splicing instructions. Andrew actually makes it a little more complicated in that he insists in burying his cover instead of hiding it under a whipping. Which really accomplishes nothing except saving you from having to do a whipping. I would rather do a nice whipping and save the work.
It is not a really complicated splice after you've worked through it a few times. But it certainly is a little daunting when just reading the instructions. Perhaps watching the video will give you a little confidence to try it.
5/16" is actually a pretty good size to start out on.
Give it a try.
YouTube - Andrew's core to core splice Part One
YouTube - Andrew's core to core splice Part Two