I would have the barrel turned by a gunsmith to fit the slide. the extra .6 of barrel can either be chopped off and recrowned or threaded for a comp if you decide on an open gun. The higher pressures you mentioned due to added length are moot since they function in the xfives just fine. The FTE's were an issue with the internal extractor losing strength, replacing it or bending it are well documented fixes. The external extractor on the shorter slide works flawlessly in comparison.