lt1 bearings "standard"?

I have a 1997 lt1 with 85K miles. I checked a couple of main and rod bearings while the pan was dropped and they are as follows, Rod #2 .0032. Rod #4 .0032 Main #1 .0020 Main #2 .0022. The crank is in fantastic shape. I understand these clearances are a little big by the book, but I dont know if this is common for an 85K mile motor.

I bought a "standard" bearing from a local autoparts store to check clearance again as I want to put fresh bearings in the motor, and the bearing would not fit on the crank while installed in the rod and cap. It is WAY bigger than what came out of the motor. So what gives? Do i have to install undersize bearings? That does not sound right.

Are you sure the bearings are "standard". Most are sold as oversized and are usually wider. What was the brand and part number?
What does the manual say for clearance specs? I assume you are using plastigauge?

Look at the end of the bearing that you bought and also the one you pulled from the motor. There should be a part number at the end of each bearing half. If there is numbers above that it will look like .010 or something like that. That means the crank has been turned and you have over sized bearings. If there is no number then more than likely it's all original and hasn't been opened and worked. Your new bearing is probably an over sized bearing. Not often does some one go to the parts store for a standard size bearing......