Suprisingly these two model kits are compatible, the T-tail from the Victor is a good fit. So too is the inflight refuelling probe which sits on the nose of the SeaMaster, it seems to have the same curve. Then there's the wings, the SeaMasters' can be cut and glued to the section just past the under wing fuel tank and is slightly longer than the one provided in the Matchbox kit.
The main fuselage can be cut to allow the new section including the Victor's engines and wing stubs although so filler/puty will be needed. The interior from the Victor can be used.
A raid in the spares boxes should result in a suitable landing gear or I can try the landing gear from the Valiant B.2 vacform kit.
I will call this the HP Majestic but I haven't thought of a purpose for it yet.