So if I understand you correctly, you have the 74 engine out and probably on an engine stand?
At this point, all it costs is some gaskets and some measurements to determine what you have.
I stand to be corrected but I thought oversized pistons were usually marked on the top. ( .020,.030 etc..)
Compression is easily checked and if you pull the cam, that can be checked as well.
If you haven't heard the 74 engine run and you have it outside the car, it's cheap insurance to check it over anyway.
No sense gambling and possibly losing part of the cruising season when it is easily preventable.
