Nandric, did you meant SP-15? I believe that and the SP-25 require the same cut out, thus fit into the same plinth. The SP-10 and SP-10 Mk 2 and Mk 3 have a different pattern, thus fit into a different plinth.
For the OP, it should not be difficult to fabricate a new armboard to drill for the PT-5. The main question may be should he utilize marine ply, solid hardwood, aluminum, acrylic, etc.?
For the OP, it should not be difficult to fabricate a new armboard to drill for the PT-5. The main question may be should he utilize marine ply, solid hardwood, aluminum, acrylic, etc.?