I have a rubbish made arch going from my living room into the kitchen ,its plastered & papered either side ,done about 20 years ago from the previous owner of my house ,1 side starts to curve at 5ft the other side starts to curve at 4foot ,been winding me up for years & I am looking at ideas to get rid of it ,possibly square it of & maybe put a plaster or MDF casing all round to finish it off .make it look even,is this a handy man job or joiner ,looking for advice & ideas if anyone can help ,don't know were to begin.Liverpool area thanks