The mount, as used on theL96A1, was made to hold S&B scopes so they are 30mm rings. I cannot find a reference in any publication as to the size of the dovetail on top. All that I could find on the net was this:
Accuracy International Mounts are machined aluminium one piece mounts with elevation built in (MOA). All 34mm mounts can be converted to 30mm using reducing rings.
Part No Description
3051 30mm STANDARD DOVETAIL MOUNT (28moa)
3027 34mm STANDARD DOVETAIL MOUNT (18moa) - USE ON .338
6371 30mm MOUNT FOR PICATINNY RAIL (18moa)
2970 34mm STANDARD DOVETAIL MOUNT (28moa)
3436 34mm MOUNT FOR PICATINNY RAIL (28moa)
3108 34mm MOUNT FOR PICATINNY RAIL (18moa) - USE ON .338
5656 34mm MOUNT FOR PICATINNY RAIL (45moa) - USE ON .338 DOUBLE TURN SCOPE
4276 34mm MOUNT TO FIT AW50 PICATINNY RAIL (45moa)
4321 34mm/30mm REDUCING RINGS (set of 4) (4 hole)
4323 34mm/26mm REDUCING RINGS (set of 4) (4 hole)
5655 34mm MOUNT (45moa) - USE ON .338 DOUBLE TURN SCOPE
That's certainly the L96 scope brackets. However, before you buy, IIRC the bottom of the mount has a lug that sticks out that fits nicely into a corresponding hole on the sight rail so you can guarantee the sight goes back on in the same place. So it may not fit on your sight rail unless you drill a hole.