One of the telephone collector groups, TCI or ATCA, might help you. There's a big outfit in Wisconsin (I wish I could remember the name -- I think it's "Ron's phones") that has a big inventory of old stuff. (Maybe someone else could post the correct name?)
I don't know what a HAL 6000 interface is. But keep in mind the older machines use Baudot which is not only a different code, but requires an extra control character to shift between letters and numbers.
Being mechanical and complex, the machines will need servicing. If they hadn't been used for a while, they made new repair/adjustment to work again. (We had some fans stored in the garage for a number of years. When we tried them, they were just dead. Trying to twirl the blade didn't help.) Also, old machines had shellac or fabric insulation on wires which can rot out.[TELECOM Digest Editor's Note: Maybe my brain has shellac or fabric insulation. Lord knows it has been rotted out now for a few years, ever since the hospital got done with me. PAT]