I would personally concentrate on getting everything into Bootstrap Studio but stay in the Bootstrap 3 format first. Updating the links is easy enough to do for the moving of the main image folder in the root to the assets folder.
Your map which was done in illustrator was probably exported code and added ? I have simply downloaded that page and imported into Bootstrap Studio using setting Bootstrap 3 when creating a example project. If you rearrange the links to above and below your map and set the map to 100% width and 100% height and then contain them all in columns you might be fine. just a thought… Example Map
Later if you feel comfortable in Bootstrap Studio using the version 3 you could update the site to Bootstrap 5 but be aware Bootstrap 3 was Desktop down and all the media queries will have to be converted to mobile up which started in Bootstrap 4. That can be some work but …then with the help of AI it might be alot easier.