Hi all. In trying to learn SW, I often take existing 2D drawings and try to replicate them into a 3D model that I then try to detail into 2D again to compare with my starting drawing. I find it's a good way to practice. Here's a detail of the current drawing I am trying to replicate:

Note the fairly obvious red circles. The lines inside indicate the center of both radii. I know I can use the center mark tool to create a center mark, but they are huge compared to this. I can change the Display Attributes and size the marks down a notch, but that doesn't look too good nor similar as the marks extend in all 4 directions and the current drawing as you can see only extend from the part surface so to speak to the intersection and little beyond that (in the case of E. The R6 is a bit different). I know that with a Center Mark I can extend the lines or end s I choose by clicking the point and dragging, but I can't seem to shorten them.

Could anyone suggest workaround that would help me approximate the desired effects? Sketching seems like a cop out.

Edit: while I'm at it, how do I detail the threaded hole? I made the holes in the 3D model using the hole wizard, DIN ISO M6.