I used the Chevy tube for the front piece of my 2pc shaft.
I had to turn a few thousandths off the Mazda yoke & weld it in to the tube, but I used the rear Mazda shaft.
The tube thickness differences between the two is not worth mentioning, so the Mazda shaft works just fine.
There were no problems with this setup until the rear end locked up.
I also used my Mazda fuel pump for four months. The reasons I changed it to a Chevy pump is because the pickup screen was torn and trash got in it...
AND it was cheaper than a Mazda replacement.