Certainly finasteride would block a lot of the DHT conversion at the scalp and decrease the amount of hair you will lose on a Test cycle. If it is as little as your past Eq or Primo cycles is difficult to guess. Depends i might say on your dosage levels.
Primo and Equipoise are not as anabolic as Test, so you would need higher doses of either of them to have the same anabolism as cyp, enan, etc. So for a example if you took 1 gram of Primo weekly that would be something like 600-750 mg of Test. If the dosage were made to have the same anabolic effects like this then my guess would be that with the finasteride the Test cycle would be about as mild with the harline as eq or primo.
Remember if you are using finasteride in the form of Proscar to cut your tabs into at least four parts as only 1mg ED is needed for hair loss.