I'm not very knowledgeable about engines but I don't think an engine strong enough to fly these vehicles cannot be derived from the TS1400. Also, I'm not sure if a decent turbofan will come out of a civilian engine with a radial compressor, which is difficult to use in the military. Of course, it would be more correct to ask @Nilgiri .
Yup, clean sheet start is best for Turkish turbofan programs given the radial compressor here.
Radial compressors have sweetspot reasons at this size, but their disadvantages grow considerably if you want to scale up the engine. Both the investment in cross sectional area (per compression ratio ability) and the design needed to transfer this compressed air to the combustor (it is reverse flow combustor like PT-6 I believe, who's benefit again lies with this particular size range ). i.e Reverse flow plumbing and orientation wont work for turbofans (given the literal fan)....they are turboshaft/prop specific.