I have been debating this for a while. I know the T61 can make slightly more power than the SP60, but I have heard the SP60 is better quality. Although both of them are now discontinued, there are still a few more to be bought out there.
I am going to get another fuel pump (maybe Walbro?) to run with the stocker and add an aftermarket fuel pressure regulator to deal with the single turbo, but I still wonder if the SP63 would be safe with an otherwise stock fuel system. Whatever I get, I won't exceed 18 psi until I get a full fuel system. I don't plan to do the full fuel system upgrade for at least 6 months or more.