[BLKBRD]

I'm considering purchasing a '69 GTO that was originally a 4-spd M21 car. The current owner tells me that it's got a SBC with an auto in it at the moment and it's got the original Pontiac 10-bolt rear. He's not sure if it's a TH 350 or a TH 400, but it does have a driveshaft and crossmember installed. If I purchase it, I'll be putting a 400 pontiac engine back in it with a 4-spd M21. My questions are as follows:

1) If it's a TH400 in the car now, I suspect that neither the crossmember or driveshaft will work for the Pontiac engine and M21 config, correct?
2) Assuming that the driveshaft and crossmember are Chevy A-body items and the current tranny is a TH 350, will they work with the Pontiac with M21 install, or will I have to get Pontiac specific items?
3) Will the TH 350 or TH 400 yoke work with a '69 M21?

Thanks in advance.