Good job!!
Grounds are the most looked over part of an electical system. I put #1 cables on my VW diesel battery to the block and to the starter. I also added another ground from the battery to the chassis. The ground to the block goes from the battery to the bolt that holds the starter to the engine. Doesn't get any better than that. If you want super good cables, welding cables are great, they are really flexable because they have a ton of smaller copper wires inside the cable, unlike regular cables with just a few strands.
It is my understanding that electricity flows around the copper wire not through it so the more strands per cable the less resistance and greater conductivity.