Jonathan,
As I recall, Park's own chapter on design in The Game of Golf is pretty detailed and worth the read if you want something in his own words. It was done back in 1896 but most of it, if not all, probably held true throughout Park's career so it would probably apply to his work at New Bedford in the twenties. There is always good info one can derive and apply (carefully) to an existing course from an early architect's writings, even if it seems a bit elementary compared to the writings that are available now.
Park was one of the very first to, if not the first, to put his thoughts on paper. What would be helpful for you at New Bedford is seeing what holes/shots/features/strategies found at New Bedford match up with Park's thoughts. It may help you determine what may not be original details from Park.
For instance, Park promoted sand bunkers that were big and deep enough so balls would not roll through them or bounce out. I would use that information when looking at a bunker that was considered shallow possibly not being original (at least in its current form).
The Parks of Musselburgh (1991) is a good read and it does re-print much of Park's Game of Golf chapter in bullet form. Other than a compendium done by Frederick Hawtree with the same info, there is nothing else in Park's own words out there that I am aware of. k has nothing of Park's philosophy.