With a stock profile camshaft, the current API grade oil (SN) will be just fine. It only becomes an issue with breaking in a new camshaft, or if you're running a high lift performance cam, with or without high rate valve springs.
That said, I will second the use of VR1, I use it in my '55 235, which has an M4F Howard race cam in it. However, on my S10, with a stock grind flat tappet cam, I use standard Valvoline.
