Greetings,
I'ma C++ teacher and vastly experienced R&D engineer with 25 years of C++ experience.
Here is an identical task I under took this year, for a U.S client of mine:
https://www.freelancer.com/projects/CPlusPlus-Programming/Code-Review-existing-Application-lines/
Relevant Skills and Experience:
3 decades of C++ experience on Windows, Linux and electronics based R&D projects - working for global names in consumer electronics, government and software dev.
I'm NOT a specialist in testing though. So, that's worth bearing in mind.
Some initial questions:
a) How large is the code base?(in KLOC)?
b) What platform or O/S does the code run on?