Too much side clearance on the rod big end will allow too much oil volume to be thrown on the cylinder walls, more than the rings can handle, as well as causing a reduction in oil pressure (this is why you shouldnt use the chevy V8 rods in your 194-250 sixes).
There was an article on the Egge machine site that dealt with stroking a 261 crank by offset grinding and using stock chevy 292 rods. I think in some 12 Port News issue some one had a chevy ll with a bored 261 stroked this way to 292 inches.
On the EGGE site they had two senarios, the last one was more expensive and would solve the excessive rod side clearance problem of using the narrow 292 rod. They welded a bead all around the journal on both sides to form a "cheek" and machined it to suit using the 292's side play dimension.
On the EGGE site, they surmised that the 292 rod was suitable strength-wise over the chevy "pinch bolted" rod-I think GMCs have a more common wrist pin system, but there maybe more easily available aftermarket 292 rods around than those of Hudsons and Allis-Chambers, etc.
Dont know if GMCs and Chevys have the same deck to crank centerline dimension like the chevy 235/261 and 292 hve but this might work.
For a strip car you might be able to live with excessive rod side clearance-but certainly not in a street car(you'd need to carry a case or spark plugs with you).