There is loads of info on this site:

http://www.interford.co.uk/forums/

Specifically look under the section on engine conversions. There are loads of people that have 24vs on there and some have done the conversions themselves.

Also check out these two sites:

http://www.maddoldbugger.supanet.com/

http://myweb.tiscali.co.uk/xrcosworth/

Good luck.