Delete Dynamic Block Rotation Parameter: Keep Custom Rotation in Standard Block?

I want to convert my dynamic blocks to standard blocks but keep the "custom" angle rotation.

Full explanation...

I have a dwg full of different supports with blocks for each size/type. All of the blocks have been set up as dynamic blocks with a rotation parameter in addition to the block rotation and rotate action with the base point on one corner and rotation grip on another corner.

I need to move the base point of these blocks to the centre of each support instead of the corner. I tried to use the Lee Mac Programming “change block base point” script that lets you keep the block reference position but I can’t get it to work with these dynamic blocks - it only seems to work on standard blocks.

I hoped if I just deleted the rotation parameter in block editor the supports would just be standard blocks and keep their displayed rotation then I could use the base point script as normal but instead my “custom” angle is deleted (see red arrows in the attached grab) and I'm left with my all of my supports at the “misc" rotation of 90 degrees.

Is there a way to save the “custom" angle rotation into the “misc" rotation? Or another idea of how to change the base point?

Thanks