Concert sized longnecks generally benefit from tenor strings. It's all about string diameter. Some manufacturers make different length strings with the same diameters. To understand string diameter, visit Southcoast's string guide.
Worth Fluorocarbons for a tenor scale length sound like a good choice to me. They should provide good volume and service life and allow you to attack the strings more aggressively. The Worth C string is .0291". The Martin M620 C .0340". The Martin M600 C tenor is .0261" I believe. Thinner is normally considered optimum but there must be a reason for the variance between the two Martin strings and the Worth String right in the middle. This might be worth experimenting with.