not sure i am gonna succeed in getting these caps out they have been siiting for 2 days in penetrating oil & with the methods you advise are not budging , they seem rusted in there & im afraid i will destroy them if i continue. I think my bike is an 80-81 model as not registered yet but frame begins 3Y2 so my question is will any other forks fit with my original front wheel and drum & top & bottom yokes IE: DT etc as these are more plentiful especially in the UK .
Regards

Can you some how invert them and put in a bucket of vaporust?

Ok, get a wire brush on a drill & force it in the top bit to clear any rust that it can.
Have you tapped it down a couple of mm & flicked out the clip.
If so pour oil in the top bit & with bike on the floor keep tapping the steel bung & it'll work its way up.
Just be careful to have the handlebars over the top so you don't get an eye full of bung.
Might be enough spring preload to do all that with wheel off the ground.
Otherwise if all else fails then tie the front down under lots of spring compression [still with handlebars over the top] & keep tapping.
Sorry if that sounds dodgy & dangerous--which it is--just take care.
Think Mark mentioned drilling & tap a thread in the steel cap to pull it out.
If you did that you could add air valves after if you wanted.

Success at last & many thanks , tied down with ratchet straps and compressed just enough to take the strain off the springs and I could push the caps enough to get the clips out , it was still a struggle to get the caps  out but tapping with a rubber mallet on the bottom and they eventually came out, I do like the drill and tap idea for the future. Many thanks again . 

Well done. 

Possibly not the greatest fork design ever!