There are no replacement 261 rods of any kind available in the USA, maybe the bolt-less variety are a Brazil-only item.
Any serious Chevy racers of years gone by used GMC 228 connecting rods as they are much beefier and eliminate a point of failure on the pin bolts. Same journal sizes (I think - have to look it up) but the pin height is different, so custom pistons are required.
An upcoming Inliners article details how to use 292 rods and Cadillac V8 pistons, along with offset grinding the crankshaft, to get up to 301 cubes out of a 261. Cheap and readily available parts, as the 292 uses the same rod bearings as the small block V8. This might be worth considering.
