The Harken Dingy System was used on the Mutineer and the early Nineteens. Rod furling was not available for the smaller boats until about 1985/1986. It was also very costly at first.
I have the Harkin system on my Mutineen and I don't like it because of the twist it puts in the sail at the tack. On my Nineteen I had standard hanks and got along without the furling.
I have uploaded some of the early Newsletters and you can see a picture of Roy Sutherland on the bow of his Nineteen with this system. It is in Vol II, no 3. This link should get you to the pages... http://www.starwinds.com/loaddown.html
I tried to find the discussion of Merriman rod furling but I can not seem to "quickly."
If you like roller Furling, you might look for a current system. The rod of some slide over the forestay and are only workable on boats that are dry sailed or moored. If you trailer you run the risk of damaging the rod.
As to a new Jib you need the I, P, J, and E located here http://www.starwinds.com/stw190.html
But remember to measure your boat because Wellcraft did not cut all the stays the "exact" same. The Nineteens came with the option of a 150% which I have and like very much in light air. It is a fun sail to fly. The option package included winches and track at the windows and sail. The stock tracks need to be a bit longer and then the sail would have a better shape (this is on my boat). A sailmaker can help you with the placement.
I also added a storm jib to the Nineteen because I sailed Lake Erie sometimes. I discovered I would have been happier with a Heavy WX (44% vs 20%) sail because I did not get in seas to use a true storm jib. If you want a smaller sail than the working 110% look hard at the rough WX you sail in. My Storm Jib (20% of the foretriangle) does not give me enough power in the Lake Erie I can handle. I would have been better with a Heavy WX sail. Also you want to make that head sail change before you need it. You don't want to be on the bow in really rough WX.
Also Check Bacons & Assoc. (from the Link page http://www.starwinds.com/links.html
). They may have a good used sail that would work.