I would suggest.... nope that's not strong enough. I would highly recommend... Hmmm, no still not quite the import I believe this subject merits. Let's try: I think it would be a serious mistake for you to proceed with your "porting and polishing" work without first reading up on the subject as it applies to Pontiac heads specifically. There are a few critical areas in the ports that need work and will produce results. There are other areas in the port that are a waste of time, and there are a couple areas that if not treated properly will make your ports worse than they started out. Contact the owners of this forum and see if they can't send you a copy of Jim Hand's "How to Build Max Performance Pontiac V8s" book. It is an excellent source for the information you need to properly port a set of Pontiac heads. You can also try searching the archives of long-ago posts here in this forum as fairly lengthy discussions of this subject have been held here in the last couple of years.
My apologies if you are already sufficiently armed with information for this task.
Next up, if you find a set of small valve heads with desireable chamber sizes such as your #47 heads, you will be faced with three obstacles in the path to high performance.
First, you will need to drill and tap the end exhaust bolt holes on the exhaust flanges. No small-valve heads that I've seen have these holes drilled from the factory, including the #47s in my garage.
Second, you will need to remove the pressed-in rocker studs and replace them with screw-in studs. Failure to do so will result in a stud pulling out or breaking with any cam that can truly take advantage of your ported heads.
Finally, get the valve seats cut for 2.11"/1.77" valves BEFORE doing the port work. You will not be able to properly shape the ports to the seats without doing this. You can put a layer of duct tape or two over the seats and then be extra careful while porting to avoid nicking the seats.
The small valve heads entail some extra work and thus extra cost to make them work as a high performance head, but given the costs to purchase large valve heads with favorable chamber sizes you might break even. Of course, if you can do any of the abovementioned work yourself then you'll be ahead of the game.
Oh, and here's a picture that shows you where to find the pertinent numbers on a Pontiac head:
Pontiac Head ID