Here is a very nice Sako-Mauser chambered for the 8x60S. Sako made both the 8x60 (.318" groove diameter) and the 8x60S (.323" groove diameter). From what I've been able to find, the smaller "I" or "J" groove was found in early Sako-Mausers and the larger "S" groove in later ones like the example currently on Gunbroker. So far as I can determine, Sako chambered neither of these in the L61R, but did make a few 8x57's in the L61R.
I'd love to own the example on Gunbroker, which appears to be in very nice condition, to go with the 8x60 I own, but the price seems steep to me. I'll admit that it is a very rare Sako, but there doesn't seem to be the collector interest in the Sako-Mausers that there is in the Finland Sakos to justify the asking price. Of course, value is in the eye of the collector, and that's just one person's opinion.