I had my local chassis shop build me a steel .083" wall shaft with Brute force U-joints and a brand new slip yoke for about $200 I am very happy with it.
Odd story, My original 69' Driveshaft had the u-joints welded on like 15 degrees out of phase from each other. They said in 69' was the only year it was experimented with and the idea was to reduce vibration further but I guess it was unfounded and GM went away from it. So I still have the stocker laying in the garage. It had twisted the splines so bad in the yoke that it would not slip into my new Muncie.
If every ounce of you is about rear wheel horsepower I would get a carbon fiber or aluminum....But I am very happy with the price of my steel HD unit....And to hold it in my hand it didn't feel overly heavy.