What kind of flat tops? send a photo or part number.
What is the deck height? The amount the piston is below the deck at tdc. (Typically 0.020" but and range between 0.000 and 0.030")
Stock gm sb heads are typically between 150cc-160cc. So you will need an aftermarket head to get 195cc.
Early sbc heads are typically 64cc chambers. What casing numbers on your heads?
195cc head on a 350 is not a setup for low rpm torque. Better off with 160cc ports.
Plan on using headers for max torque.