Migrating themes

I have a seen a lot of people who want to migrate from older opencart versions (1.5.x or 2.0.x) to 3.0.x. My case is the same except I don't care about the DB. I will have a new fresh opencart 3 DB. The main problem is that I have an opencart 1.5.6.4 store with a theme called Sharty which is not compatible with opencart 3 because when the store was made opencart 3 didn't existed. The other problem is that I don't have the theme files seperate. I have the theme installed inside opencart and I need to extract only the theme files. Also I need to migrate all theme extensions (if there are any). Is this possible ? What should I do in this case ?

What should I do in this case
Well, just eat the bad pill, and get divorced, there is not a single
line in that theme, wich could further be of any use...
... or anywhere else in your old Version OC ...
Ernie