Installing 409 in qb fuse. I have the holes drilled through 711 and 409. Everything is square and nice. I can not get the rear attach plate to sit happy against 712. It will not lay flat. Bottom is tight but top is out 1/16 on one side and an 1/8 on the other. I have an 040 shim on 711 to tighten it up but it is still not perfect. Am i missing something or do i just tighten it altogether with the vs install? Also rivet holes for 712 to the skin are all off just enough to need a drill run through before the rivet can slide in. Been at this step for 2 days now. I appreciate any advise