Looks like your harmonic balance is different from my 54 235 and 49 216. They were apparantly made to accept a hand crank and your 58 doesn't look to have that capability.
54 harmonic balance

As posted you could take two 5/16's (I believe) bolts and thread them into those two threaded holes in the balance and use a pry bar to rotate.

Here's a pic of the timing hole above the starter, the pointer is visible in the center.
timing hole

Good luck
Dave

1949 Chevy 1/2-Ton 3100
1949 GMC 1/2-ton 100
In the Stovebolt Gallery
More pix on Photobucket
Video of the 216 running
Video of a Winter Cruise