Dennis,You can check the bore size to see if it's been overbored. 3.750" would be the standard bore for the 292. The amount of overbore may actually be stamped on the top of the piston, ie. 020, 030, 40, 60, etc..
Look at the backsides of the bearings for an undersize such as 010, 20, 30 etc. to indicate that the crankshaft has been ground. The original bearings are dated on their backside and should be within a couple of months of when the engine was actually built. Similarly, some of the replacement engine bearing brands are dated on their backsides with the month and year; ie. "04 86" which would indicate April 1986 and can give you an idea of when it was rebuilt assuming the bearings were not really old stock. The crankshaft may have been stamped if it had been ground undersize and there will typically be two of these numbers; one value for the amount of rod journal undersize and another for the amount of crankshaft undersize. These stampings are usually found on the front of the #1 journal but I've found them stamped also on the counterweight edges. And not all grinders stamp their cranks thus making you really look harder.
If it was just a re-ring and bearing freshen up, then looking at the backsides of the bearings for being non-Ford or having dates would be a reasonably good indicator.