It seems that the limits of the 901 transmission is about 225 pound feet. I have not been able to find much information on the design limits and real limits of the CV joints. At most I see references to them being the weak link. My new motor outputs 175 pound feet of torque. I'm afraid the CV joints will not last long. Should I plan on installing something like tarett 914 axles? They claim a limit of 300 pound feet of torque.

If the "e" in your handle indicates electric then I'd go with larger CV's. I snapped 3 914 CV's running a V8 (300+ ft lb's) and that wasn't even burning rubber. With a Suby that produces ~250 ft lb's I have no breakage issues.

Yes, it was converted about 20 years ago. I am updating with it a modern AC motor. I know that in our bug the motor made short work of the old worn CV joints and transaxle. It doesn't have anywhere near this power.

The new motor has about the same HP as 914-6 GT but with more torque across 5000 rpm. Then the regen on braking which the old DC motor does not have pretty much has the driveline under load all the time.

Is there any other axle options besides stock, Tarett, or something completely custom?

Blind Chicken Racing, CV101 may be able to help you. Try 930 turbo cv's

Give the stock ones a try and see what happens. If they break you would have to upgrade anyway. If not, then you have your answer.

Brand new ones are pretty strong. If there's any wear high HP wil lunch them quick.