it doesn't matter
Calligraphy and painting are art, and art is about "art"! There are no restrictions.
As for the choice of font, it depends on which aspect of your real cursive seal script is more prominent, so choose which one.
If there are black squares on the paper, you don't have to draw them word by word. You can use one word to occupy four or five squares and another word to occupy half a square.
There is no need to leave a blank at the beginning, write vertically in the sky, or write horizontally near the left.
Punctuation marks or partial punctuation marks can be marked.
It can be branched or unbranched.
-this is "art" and this is "venting emotions"!
The final mosaic may or may not be present. You can also have a small seal.