The two lower fuses in the picture are related to the charging and can be sized either on the charging rate of the alternator or the size of the cable you've used. If you've used 35mm cable between the ACR and the house and starter batteries, then either a 75A or a 150A will be fine.
For the main fuse block, it's dependent on the cable size which in turn is dependent on the electrical load from the consumers. I'm guessing that the consumer load won't be more than about 20A - VHF, chartplotter, bilge pump etc. As a result you can get away with quite a small wire feeding the fuse block - 6mm with a 40A fuse for example. It is all dependent on what you are running.