Oops, somehow missed that. For a slant six, there are two adjustment screws for the distributor, one at each end of the bracket. So undoing the one at the end of the bracket may get you enough to reach your timing target. If it doesn't, pull out the distributor and move it one tooth.
Man, you have no idea. I miss stuff in titles daily. lol Don't forget, there are two adjustments on the slant 6. One on top and also one on the bottom.