As far as I know, no one makes a helical cutter head for the Parks Planer. I guess that it would be nice, but with proper setup you can do some excellent work with the standard planer blades.
I bought my Parks in good condition but with some surface rust about 50 years ago from a dealer in Los Angeles .Cleaning it up was quite a chore and ultimately, I took the machine all the way down to its gutty works.to get it nice and clean. That took most of a gallon of 70% phosphoric acid and a lot of scrubbing and scraping as I recall.
Mine has the factory stand but it needed a dust collector and a belt guard.I made those out of riveted sheet aluminum at the time but it needs a better belt guard so I'm in the process of making one out of 1/8" cold-rolled steel as we speak.
As I mentioned earlier, my son wants to build a guitar and wanted my help. In the past the Parks has done excellent work planing guitar woods down to as thin as 2 mm. The wood is held on a piece of MDFB with double-sided carpet tape. With nice sharp blades, properly set, it does a great job.
We have the wood for his guitar now. It's a set of Pao Ferro (Bolivian Rosewood) and the backs and sides came from the seller band-sawed to 3/16".
I have lovely piece of quarter-sawn 2"X10" Sitka spruce for a top that I've saved for many years. I'll re-saw that on my 14" Delta band saw and then plane it to size. I added the factory 6" riser on that years ago so that I could re-saw with it. It takes a longer blade (105"} with the riser. I use a 3/4" 3-4 skip-tooth blade for that purpose.
Anyway, a good planer and band saw are lots of fun!