thank you very much, Gilberto, for your tips quite a few years ago. I have tried to follow them up, as well as some other useful links that you gave to other people on these pages.
The Wilhelm Klein who arrived in Santos in 1920 was the wrong age. Our Wilhelm would have only been around 18 at the time. There does not seem to be any arrival listed for him.
We have since found out more: He married a girl from Limeira and took overthe running of her family's honey farm. But we can't find a name or location of this farm. On the useful jusbrasil.com.br/diarios pages, we found him again: various business dealings in 1955 and 1956, as well as taking on Brazilian nationality in 1956. By that time he called himself Frederico Guilherme Klein and had a son, Guilherme Klein.
That seems to be the end of our findings. I wonder where we could research Wilhelm/Guilherme's marriage, birth of his children and his death, presumably all in Limeira. And maybe he entered at a different harbour to Santos? Perhaps residence is listed somewhere?