John -
No, the shrouds are not the same. There are several differences.
First and foremost the dash/scuttle area is totally different, and you will have to the back off the BJ8 shroud to mate with your BT7 shroud.
Secondly, MkI BT7 and MkII BT7 shrouds are different in the grill area - the MkII and MkIII grill holes are different and the part between the grill and bonnet are different - the metal has a different lateral curvature. A MkIII/MkII grill will not fit properly in a MkI shroud.
There are essentially four shroud variants used on 3000s:
Mk I BT7/BN7 shroud
MkII BT7/BN7/BJ7 shroud (revised grill profile)
MkIII BJ8 Early (revised dash/scuttle area)
MkIII BJ8 Late (revised turn signal layout)
Hope that helps!