Colin, a tad unfair. The 14W motor was fitted to the later cars in the series, and certainly later spitfires and GT6 had that motor. And technically no, most wiper motors couldn't be fitted. But you knew that.
Sorry Clive, didn't mean to be unfair, but the OP wanted a 2-speed MK1 motor and it is true that by changing the mounting, wiring and drive gear then you can fit almost any motor, and I'll modify the post to say 'almost'. Mini, MGB, Triumph, it just depends on how you want it to look. I don't think it was being unfair, or sarcastic, to point this out - fitting an alternative item, even one from another Triumph, can mean a lot of work to someone who may not be able to fabricate their own mount, adapt the loom, calculate angles, and source the correct drive gear from a selection. If the car is a Mk1 then it's not unfair to assume that it already has the loom connections, and switch for, the 2-speed, unless it's missing absolutely everything and has to be sourced from scratch. So: I was trying for the straightforward option, an original replacement that will require minimum work, and am still looking.
I'm sorry Roger took it this way; I was expecting a reply along the lines of: "well, it's not that difficult, this is what I did..." sort of thing. I didn't think it was being silly, or being an idiot. It's certainly not sarcastic, but a valid point, and one which I hoped would invite discussion and debate.