G'day Roland,
That looks like an Australian email address, which may be supported by you using metric volumes.
If that is the case, then the Australian Distributors of West System is ATL Composites on the Gold Coast, see link below. They have a couple of handy little booklets on their products available free by mail, or on their website.

If your S&G instructions are from the US, then I suspect the volumes quoted are in US gallons, each equivalent to 4 litres. If they are imperial gallons then the conversion is 4.5 litres to one imp gallon. Assuming US gallons would yield a total of 9 litres of epoxy.

ATL package West Resin in 4litre containers, with either 800ml hardener for the 5:1 normal mix or 1.33litre hardener for the 3:1 clear coating system. You will probably need the latter.

That makes the respective volumes either 4.88 or probably 5.33litre per pack.

They also pack their fillers in 1 or 4 liter containers. One quart is roughly equivalent to a litre.

For scarf joints, their 403 MicroFibre blend (both silica and fibres) is ideal.
For fillets, either 411, or 410, depending on what you want to do.

I havent been able to find a source of wood flour in Australia, not that I have looked hard, cos I use sanding dust or sawdust from the timber I am using.

I would start with a litre of each of the 403, 410 and 411, then go from there if you need more - you will have the experience to purchase what makes more sense for you, on your job. The incremental cost for smaller pack sizes is not significant for the volumes you need.

Hope this helps, and if you are not in Oz, then the website may be of use anyway. Good luck and enjoy the building process!