chimney

I have an old solid wall sandstone barn / cottage (approx. 150 - 200 years old), I am having the dining room plastered however there is rising damp on the external walls and around the fireplace. The old plaster is onto a cement rendered wall with bitumen damp proofing however this has failed...

OK, searched the forum and didn't get a cut'n'dry answer so here goes... Chimney breast to skim around multi-fuel stove. Cement board on metal stud construction with areas that will exceed temperature for gypsum plaster. No problem with priming but... What high temperature finishing plasters...