Harmonic balancers and engine balancing

I would like to use a liquid filled balancer on my new 347. Right now I have a Professional Products Harmonic Damper that came on the engine when I purchased it. A friend of mine has a NIB Ford Racing fluid filled 50 oz balancer he would sell me for $100. He said it cost $280 new. My question is, my balancer has a weight screwed to the inside. I am not sure but if I change my balancer to this new one will my engine then be out of balance? Or are all the 50 oz balancers weighted the same? I am not sure if the engine is internally or externally balanced and how would I tell? Here is a pic of my present balancer.

Well first off you have a 347 balanced to 50oz? That would be very rare, always balanced to 28oz. Let's assume your 347 is 28oz external, 99.9% chance it is. Unless the ford balancer has a bolt in counterweight, its useless to you, also nothing wrong with the PP balancer, yours is the 80006 non sfi model, I got a heap of guys running that balancer making 400-500hp.

Thanks woody. I assumed that since I have a 87 block that it was 50oz. I apprecieate your info. I will keep the one I have.