We had a tranny rebuilt about ten years ago and they didn't put the bushing in the front pump for use with a turbo spline input shaft. It lasted
3/4 of a run.
Also we used to run a mounts like what you are using, now we just run stock mounts with longer bolts in them so they bottom out and get about a 1/4" travel. Even though it should never move and if it would come apart the bolts keep the case from coming out.
5.60's 1/8 in a 4 link car and haven't broke a tranny case in a very long time.