The common belief is that the cause of the cam problem is the cam gears are just compression fit over the camshaft stock. After some amount of time, the cam gear slips on the shaft and, since the SHO engine is an interference engine, damage occurs when they slip enough. Common preventive options are to have the cam gears pinned or to have them welded. The two both have inherent risk associated with them.
If you go the route of pinning, there is a chance debris could get into the oiling system or wear surfaces and accelerate wear. Also, the pins can shear and the original problem will still exist.
If you go the route of welding them, you could get welding slag in the oiling system, the welds may not hold, the weld may warp the cam and/or gear, or the weld may be too large and cause interference with the bearing.
Just because it hasn't happened in 130k is not an indication that it won't happen or that it's already been welded. If you're looking at this from a private party, and the seller is alert enough to know of the issue to have it fixed, they would certainly let you know that. It may be in your best interest to attempt to contact the previous owner about it.
You may want to review the cam failure issues at
www.v8sho.com for more information and draw your own conclusion.
-Rod