Chrono second from Omega Speedy Mark II to Speedy Pro

The tube of the hand will fit on the post of the movement, but that doesn't mean it will look right.

Hand lengths can vary between models - I believe the Mk. II central chronograph hands are 14 mm long, and for the regular Speedmaster Pro they would be 14.75 mm, so using a shorter hand would look off. Also, the Mk. II hands are perfectly straight/flat, where the Speedmaster Pro the central chrono hand and minute hand will curve at the end to avoid interfering with the domed crystal...

Just a couple of things to consider.

Cheers, Al