Thanks guys.
Yes, a bare frame. I think it's like the CB400, a spindle goes through both sides of the frame and a tube in the centre stand. It's seized inside the centre stand tube. This is the last thing to remove.
Looks like the only way to remove it, is destroy it
I took the frame to the powder coaters this evening. They will try heat to get the stand off, by baking it 1st. If no joy, at least it will remove the grease and penetrating oil, they are happy to powder coat the frame with the stand in-situ. I'll do that, as money is tight, after what I've spent on the bike so far.
But this bike constantly has a sting in its tail! With everything off the bike, the frame was on a lift (under the two bottom frame tubes at the front) and the centre stand. I had a moment of cold dread when I noticed the lower frame tubes are out of line with the centre stand. After measurements, I'm happy the frame is straight. The centre stand isn’t! So, I would like to replace it, but I'm on a budget, already blown on the engine! So I'll live with it for now. But, thanks for the replies.