Cool!
I don't believe the stock case being 3-bearing only is such a weak point for the power output and duration of that output we talk about.
Failures of engines usually is a misconception of the parts used and more even so: incorrect maching and/or assembly of parts, but thats just my take on it, so don't let that put you off of your project
I just took my totally stock 914 2.0 engine in my street 1303 today to 305 Nm and 222 hp with the addition of a single turbo... The type 4's are great little engines
The apfelbeck project is not 'mine' though and AFAIK, its not moving at all at the moment