Your title said you are not a rivet counter so why are you counting, place as many as you think looks right, because no one else will count them to determine whether you are right or wrong. In fact most of us will not even know if there are any rivets at all on the model, unless you are entering a model judging contest.
This is a hobby, so please enjoy it, because we will all enjoy to see your model's picture's posted on here, and please include pictures of how you have done your rivets, and the completed pictures.
I assume it is a plastic/electric model, not a live steamer?
Tichy and Grandt Line both make plastic 'rivets' on a sprue. You can cut them off and pop them in a hole, or cut off the heads and glue them where you want them.
Another option is to make a smokebox "wrapper" - a thin piece of styrene or brass that covers the outside and meets underneath. Then you can punch fake rivets in a line along the edges. Do a search for rivets if you want some more advice on the punch.
another thing that works good is to take titebond wood glue, place a quarter size amount on a hard surface, take a 8 penny nail or something equivalent with a sharp point, dip into the glue and dab onto the boiler, it leaves a small round looking blob that really looks good.
Or thin the glue some with water or alchy..use in a small syringe..a drop per rivet.
You can study this approach watching the highly detailed warbird modelers detail huge RC model aircraft..exactly how they add rivets to cover a complete plane...hundreds of rivets worth btw..
its because i have no patience for stuff like decalse, and my smokebox is not flat at all, becuse when it was cut shorter, it shattered in the process, and with no styrene, or bress it was filled in with anything i could find, wood glue, sawdust, caulking,and fiberglass resin. so the surface is not level at all, so decals would never adhere even though the smokebox received a TON of sanding.