It sounds about normal to me. Look at the photo of the Boeing. Look at the nose moment to the wing. The front of the fuse is just where the cowl/nose ring mounts to the fire wall. Any plane that had a rotary engine is going to be tail heavy when you model it. In this case it started life with a OS 1.20 pumper, then an RCS 1.40 gasser then finally a Brison 40cc gasser. There was several pounds of lead in the nose ring. Even with the Brison with the battery, ignition, and switch mounted up front. Even my lst Sukhoi 29 required lead up front in that long nose with the Brison up front.
Anyone that builds should know up front about the rotary fact and the plane will be tail heavy. I knew this and as light as the aft section of my Sukhoi was built it still required lead. By building the aft section light it didn't require a lot of lead but I still had to add some.
Nothing strange about it. the rotary engines are very heavy. Not everyone cn just afford to swap an engine either. I have a very good selection of engines, my G-62 may have done the trick on my Suk but it was just way too much over kill just to get the CG correct.