at present (in the 0.5.20 area) the highest level in the gso IS level3 and in geocorp is level 1, and after this point it is find/craft the block to unlock the block for purchase in the trading posts/terminals, and the non GSO blocks can only be sold through the trading posts not the gso delivery cannons or scrappers
A good seed (for me) would be you spawn close to a crossing of the four biomes that all are large, were one of the trading stations spawn in the crossing. Also find grade 4 and 5 fabricators on dispensers fairly close. Until find such seed, I have use "1" and "2". Don't recommend "05210", tried that when the latest update were released.