In reference to your description of the model it is EITHER an MX 8 (unlikely) or Comp I.
Two distinct frame treatments (primary visual difference is sculpted frame on MX 8) smooth side contour on Comp I.
Both detachable trigger group guns of the era.
Although most stocks of the era will interchange to some extent, the Comp stocks will not match up with the lower rear points of the action of a MX8. leaving the metal proud.
Most of the Skeet specific guns of this era sported slotted "Fish Gill" style ports behind the muzzle.
