Check out the Grace Spitfire website at
www.ml407.co.uk
for a contact address. If you write explaining what you want, Carolyn will send you an application form.
The cost being mentioned here is about right, as is the waiting time, though older people do tend to get their turn faster! Also an advantage if you can fly at short notice.
The engine is out at the moment, but from what I understand the spare is now ready and will be fitted once some other routine work is done now that there is access to the engine bay.
It should be ready for next season.
RD