engine problem

Hi there everyone new 2landyzone i have just done a head gasket on friends disco 300tdi think it got cooked but now its done and running im getting back pressure in the cooling system think the head mite have had it i got 200tdi head of landy was thinkin of fitting that head 2me mates 300 block does any1 know if its gonna fit!

At a guess i would have thought not but im sure someone will tell you