Thank you, but I really want to avoid draining down the system and changing the valves at this point.Use a reducing insert on the rad and then pipe away as you need. You could use a straight through rad valve perhaps to make the overlength a bit more visually appealing.
Wouldn't bother with an extension. They are chromed and will look silly next to the duluxed piping.
Don't overthink it.
Do you have an example of the reducing insert you suggest?