This may help (probably not): 65-68 Lobro-style half shafts for 911/912 are NLA for the most part (GKN stock is few and far between; EMPI offering is junk). After a lot of research, I built two sets of axles using Taylor Race Engineering custom-length axles and 33-spline GKN-Lobro CV joints/boots from Pegasus Racing. The cost is around $800 per set. More information may be found
here. You may be able to do the same for 944/951.
Peter
On the work bench assembled:

Installed: