strange timing issue

There is a second bolt under the distributor. It holds the hold-down plate to the distributor body. Use the correct wrench to loosen this bolt with the distributor installed, or remove the distributor and use a regular wrench. Move the plate relative to the distributor to get the additional movement you need to include a range of about 2° BTDC to 12° BTDC within the hold down plate's slot where it attaches to the block.

As for your rotor-to-cap phasing: the distributor might have been installed incorrectly (governor cam installed backwards, distributor drive pinion improperly phased). If your timing mark is at verified-TDC with both frontmost valves closed, your cam timing probably isn't off by far, if at all.