Well it's now working spot on my problem was with not adjusting the throttle cable correctly. I now have a smooth idle and a nice full throttle. The mower also stops correctly when the throttle is moved to the stop position.
Today I polished a seperate engine head after soaking it is degreaser and pressure washing it about 10 times. I am going to put it on during the week. That should compete the mustang. I know it's not completely original but I am only learning this restore stuff. Ill put some photos up once complete.
Thanks for your help gizmo. It is appreciated as always.