I believe this is Canadian western red spring wheat flour traditionally. Hi protein content. Used in Italy for pizza et al.
Going to ask a silly question here - what is manitoba flour?
Now embarrased because I saw the rest of the question. I think red spring wheat is the same whether in Canada or US. I recommend googling red wheat flour.
I found it finally. Teitle Bros. in the Bronx. Ask for Eddie. He either has it in stock or can get it. (718) 733-9400