I understand the company which did one of the rebuilds is under the gun from the FAA as a result of complaints from operators, too bad they are the only game in town around here.
Kelly by any chance?
And, as for TCM GTSIO engines, Continental still makes these new, as well as new parts, so this should not be a problem.
In fact, the GTSIO engine is considered one of the best engines TCM ever produced.