I'm not sure there's any real benefit to doing synthetic rigging on a small daysailer like a Hunter 18.5.
I have worked with Annapolis Performance Sailing in the past. I've mailed them my old standing rigging for replacement on my 15' boat, and this past off-season, I sent them uppers and forestay of my bigger boat. They examined them and advised they didn't see any issues, and we happy to replace them if I wanted, but they didn't see the need to do so. No visible cracks or rust stains (it's good to be on a freshwater lake.) It was good to get professional confirmation of my own assessment.
The one thing they did say was that I should have left my turnbuckles in the fully rigged and tuned position, so they would know if there needed to be any adjustment in wire lengths. (I had spun in the turnbuckles so that they would fit in the box easier.)
www.apsltd.com
There are other places who would provide the same service. I will vouch for APS after dealing with them for several years, and when I can get to Annapolis, I always visit them, even if I don't think I need anything... but somehow, there's always something to pick up! I've also bought all my running rigging line from them.