If you don't need adjustable pushrods due to a cam choice, don't install them. If you are staying with stock cams and stock lifters, stay with your solid stock pushrods. As Thermodyne said, it's easy enough to remove your stock pushrods, and gives you the opportunity to inspect your top end. Not only can you check rocker arm end play, but you can also check for wear on the diameter of your rocker shafts and rocker arm bushings.
Installing adjustable pushrods without need gives the opportunity for interference (noise) between the adjustable pushrod and pushrod tube that so many write about, and it gives you the opportunity to set their length incorrectly. Just one more potential source of a problem for no good reason...
Pulling your stock pushrods out the top is relatively simple if you're at all mechanically inclined. Pull the tank, pull the rocker box covers and it's all right there. Clean/replace your breathers while you're in there. Use a torque wrench when putting it back together, per your service manual....
