I know you dont need this car driven any time soon,

Are the yoke and rear mounting up OK?
If so,take the drive shaft to Mikes drive line on Nebraska,and few blocks SOUTH of Busch..
Have them make you a custom shaft,if you want alimunum,they can do it..
They will have it fitted with u joints,that are replaceable.. it will cost money,but its better than any Mazda OEM one in the long run,I seen Turbo driveshafts go up for $150. thats about the cost of the new custom shaft..