Thanks Dave, but run into a snag.
The reducer output thread is 43mm. Even stepping down to a 42mm T thread, to retain strength, the ring would essentially need to have an inside diameter not much larger than 1.25"... which is what I already have!
Ordered the Baader M43 to T2 adapter from Steve anyway - should be SOME increase in diameter over 1.25"
Seems like I will lose too much light spread for my liking, but we shall see.