It depends on your region and geology, and what kind of top soil is present in your area (many factors there, including precipitation, exposure, residential lawn treatment, etc.). But good top soil is always something great and something most indoor growers just don't use enough!
I'd say, take a sample and get it tested at a lab like Logan Labs or Spectrum Analytic. It will cost you around $50 and thats cheaper than buying bags of soil. After that, you can send me a private message or post the results here (private info redacted, of course) and I would be happy to make a soil recommendation for you.
Top soil can be rich in organic matter and also have a high CEC. But it can compact a bit easier, so you will need to expand it, both mechanically and chemically. Meaning, you would need to add something like perlite AND calcium sources like calcitic lime.
Are you in the habit or reusing your old soil? Can you recycle and add back some top soil? Unless you really have amazing aerated top soil, I wouldn't add more than 35% top soil to your mix.