Hi I’m sorry to read about your dads diagnosis. 
everyone’s treatment differs and depends on many factors. 
I too have COPD although moderate  and had lung cancer 5 yrs ago. My tumour was smaller than your father’s but I had many tests to determine suitably for having general anaesthetic for surgery and fortunately my lung function test meant surgery was possible. Had right upper lobectomy but No other treatment afterwards other than close monitoring even though there was another nodule on left side. 
5 yrs later the left side nodule started changing and had surgery again ( bottom of left upper lobe removed ) for stage 2 lung cancer followed by 4 rounds of chemotherapy as there was 2 tumours removed. Again lung function tests performed prior to the surgery. 

I suppose your dad’s treatment will depend on many things and the tests they perform are the best way to decide your dads fitness for the treatment plan they consider and a team of professionals involved in his care  will determine the best course of treatment for him and this will be discussed in an MDT meeting once all results are back. 

although my COPD was no worse by my 2nd cancer event, and lung function test still satisfactory I was surprised and relieved that they would operate again. 
I am female and first occasion of lung cancer I was 52 and I had last surgery November 23 aged 57

on both occasions I was the youngest in the hospital having this cancer surgery, most were in there 70’s & 80’s so don’t think for a minute that his age will determine whether he gets surgery or not, it is very much dependent on his suitability for surgery re his fitness. 
it’s quite a scary thing to go through but I can honestly say it wasn’t as bad as I first thought. The entire team looking after the patients are the very best in the business and so very reassuring and caring 
The chemotherapy second time post surgery wasn’t as bad as you read but that was my experience and obviously everyone is different 

the hardest part in all of this journey is the waiting for results and answers as to what happens next and when it will happen  

I wish your dad the very best going forward and send my best wishes to you all