Supposedly the so called illegal turbo utilized by the Gallina's '84 T was purchased by RJ Pike some time ago. Not sure where the rumor came about of the 63 size. I'm sure if someone forwards this to RJ he can probably offer more information.
Last I heard it wasn't bigger than a TA-33 internally.
We need to make this a sticky since it gets asked once a week. I believe a 62 is the biggest you can go in stock housings. That's what I asked for when I ordered mine and by looking at how paper thin the housing is I would say I'm right. I'm sure you could also go anywhere in between also. If I ever get a digital camera again I'm going to post pictures of this turbo.