http://shop.hunterowners.com/prod.php?4881/
This is an interesting looking idea. Converting fuse panels to breakers for around $5 a piece. It also would keep the same panel, thus the same size footprint.
I am considering this idea.
What size breaker would you suggest?
Your breakers should be sized to protect the wiring that is connected to them, i.e., they are to protect against the wire overheating and causing a fire. So check the ampacity charts for the wire size you are using and size the breakers accordingly. The loads should be protected separately and individually if they need to be with fuses in the circuit. Some devices have their own protection and don't need any additional.
Blue Sea has some info on their site that might be helpful. Here's a related article... https://www.bluesea.com/resources/95