Need help and tips on ghostwriting

I've been given an opportunity and contract to ghostwrite a dying man's story.
I'm a published author of 7 books, but have never ghostwritten.
My client has access to a computer but he prefers to use a tape recorder as he is mostly bed ridden.
He's in Florida and I live in New Hampshire, so face to face meetings will be few if any.

This will be challenging but I'm excited and up for it. My biggest concern is keeping to a 3 to 6 month deadline (no pun intended) but that is kind of an issue here.

If anyone here has done ghostwriting I would appreciate any tips to help this process go as quickly and smoothly as possible.

Thanks.