I would. I'm no expert but I asked around today and it was pretty evident that it would be best. OH! And I thpught maybe if I responded..someone else would join in to help you. I personally have asked about which cam to use for N20 and no one helped. So good luck!
The new cam should fit the old bearings, but depending how many miles are on the old bearings you may consider replacing them. I would just slide the new cam in and save the bearings for the next rebuild.
I'm going to take the other side on this one. If you're going through the engine with it out of the car, replacing the bearings is no big deal. But if you're doing a cam swap in the car, leave the bearings alone. Unless it has so many miles that you should not be putting a cam in it anyway, you'll cause more problems than you'll solve. It is easy to get the bearings off center or out of rotation to the oil holes and darn near impossible to swap the rear bearing without pulling the rear cam plug - which you can't do with the tranny attached to the engine. I've done dozens of cams in the car and have never felt I should have changed the bearings.
If for any reason, the car has the original nylon toothed timing gear, take it out and throw it as far as you can. They may have been quieter than a steel gear, but were they prone to failure!