The easiest way to tell is the length of the bypass hose from the pump to the head. Just like a B/RB, the 170 has a shorter deck and the hose is only about an inch and a half long. It looks like the nipples would be touching and you'd have to pull the pump to replace the hose. The 225 is tight too, but not nearly.
The numbers are also on a pad near the alternator where the head meets the block, but they are rough to read. The 198's were later and didn't come in the early cars but someone could have done a swap.
When you figure out what it is and how much you want let me know. If nothing else I could use a head and some other spare parts.