sort of thought morse taper was same angle just larger for the different sizes ???????
Thought as much

trying to turn an adapter to hold and centre a chuck to an rt.
tom
You can probably get away with a shorter than standard taper on an RT, so cutting with the top-slide is probably easier
So first determine which Morse taper you have - The gauge line is the diameter of hole at end of the socket so measure this:
MT1 = 0.4750"
MT2 = 0.7000"
MT3 = 0.9380"
The simplest way to set the top-slide is to dial it in with known good taper mounted between centres:
Put a bit of scrap in the chuck turn it to a sharp point then put a centre in the tail stock and make sure the two align with each other point to point (if you don't check the setting of the tail stock first there's no point in buggering about with the rest of it)
Mount a dial gauge on the top-slide, set the height so the tip is exactly on the point you've just cut and the shaft is level with the centre line.
Turn the scrap around in the chuck, face it and drill a centre hole. Mount your MT? good centre with the point in the centre hole and, in the hole in the back of the good centre, a dead centre in the tail stock.
Set the top slide to run roughly parallel with the face of the Morse taper, run it up and down checking with the dial gauge and tapping in back and forth (for a couple of hours ;)) until it's right.