They only do Puch's
My understanding is that they have a really good fast local machinist for the Case Boring & aluminum welding needed for the big kits.
I assume that they do a fine job with the case matching and rebuilds of the e50's as it's a pretty basic service which they have done for a long time and they now perform in house. The time lines on this are now improved because it is being done at their Kalamazoo location.
They farm out the za50 rebuilds, but I know for a fact that those motors are really well re-built.