I have many many years of experience with both languages, as well as maintenance programming.
I assume you want the conversion to managed c++, let me know if that is not the case, not that it matters, I can do unmanaged as well.
I am a little unsure what you mean by 'should not rely any Dlls', as this is how windows works, are you implying the c++ version should not use the Alpha VSS api?
I agree with your milestone terms entirely, this is how I do most of my work.
I look forward to hearing from you, to discuss more details and maybe clear up a few queries.
Kind regards