I was convinced that opening head is not big deal and only head gasket will be changed in addition.
When head was opened I was told that pistons were not fixed and could move a little side wise... That is piston rings also need to be changed. Opened everything and this is the condition of one of the pistons. Not sure if they are very bad or just used.
I didn't notice any lack of power except when AC was On. Just smoke when starting after parking car for some time or morning start.
The mechanic confirmed the Valve seals are also bad. It is baleno 2000 and rings were never changed before. First time head is opened.