There are many companies who would probably bid on such a job in addition to GE. Wood Group and PetroTech are a couple that come to mind. Depending on where you are in the world, you might try some of the local turbine equipment/service providers who have global associations.
In fact we are working for GE - Pakistan to find out an EPC company for Naphtha Fuel system for 2 x LMS 100. At this point of time GEA is interested to do the job but as packaged/modulized the system