Morris Minor Owners Club

In the near future, I am planning to fit a servo (I have discs on the front) and replace the pipes and flexi's at the same time. My query is whether to replace the seals, particularly the master cylinder. I will be removing the master cylinder anyway so it seems a perfect time but my issue is that there is nothing wrong with the existing seals. I am a believer in "if it aint broke don't fix it" and I have seen many references on here to poor quality replacement parts.
So what does anyone think? "to replace or not to replace"

How long have the seals been in the master cylinder?
I would normally agree that if it is working leave well alone; but you are going to remove the master cylinder from the chassis leg anyway and for a little bit more effort and the cost of a new set of seals (about 10 pounds) you will have a refurbished master cylinder that you know is serviceable. I would consider it prudent to change the seals even if they are not leaking as you will kick yourself if in a few weeks time it starts to weep and you have to start again. If you were not taking the master cylinder out of the chassis leg I also would recommend leaving the seals well alone.