That's correct. A sword would be 100sp.
Let me try and explain further. When people say "convert the game to a silver standard," they generally mean that the prices of wages and goods should be historical relative to the value of silver.
In ACKS, that is ALREADY the case. A silver piece in ACKS has, roughly, the purchasing power of an English silver penny. For example, a day laborer in Medieval England could earn a silver penny a day. A laborer in ACKS earns 1sp per day, or 3gp per month. The prices all work out on this basis, more or less.
Now, one a-historical note is that ACKS coins are a bit heavier. A Medieval silver penny would weigh about 1/300th of a pound, an ACKS silver piece weighs about 1/100th of a pound. The heavier weight of the coins does encourage use of gold, since carrying 1 pound of silver only has 33% of the purchasing power.
This was deliberate on our part. Mythic troves of treasure with tons of copper, silver, and gold both imply and necessitate that precious metals be slightly devaluaed. So if you want to make ACKS function on a historical silver standard, just reduce the weight of all the coins by 66%.