Al, I'm not questioning that is what you were told but it sounds like a mishmash of information to me. Back in the 70's (and continuing for many years) most of the Taiwan yards were incestuous in sharing designs to avoid paying for design rights, swapping or sharing hull molds, and the pedigree of many Taiwan yachts built during that time was quite cloudy. E.g. I don't know what the terms "1977 Tayana M36 Hull No. 302" is referring to, but it looks suspect to me. Bob Perry's original 37 cutter design was being built by CT as the CT-37 in the early/mid-70's and was later branded as a Tayana, perhaps due to financial arrangements being changed in the Taiwan yards. "M36" might be referring to the Mariner design first built in Japan which was later shifted to Taiwan but wasn't successful and folded after a few years, only to be resurrected again by another yard.
The point of all this is that, unless you can trace a boat to a specific yard and also have confidence in the yard's build quality being consistent over time - unlikely back then - you don't really know much about a given hull when hearing about sisterships. E.g. the ballast may be lead, or changed to steel punchings in concrete because that's what they could afford at that point...or even sand, as Terry on VALHALLA was describing to me about one Taiwan built boat from that era.
I'm not saying this boat isn't worth considering; perhaps if you did an extensive personal survey of her, you'd know whether contracting with a professional surveyor would be worth the risk. But you probably won't know much about that one boat based on her sisterships.