Complex sentence: The response to Univers was immediate and positive; he claimed it became the model for his future typefaces: the slab serif Serifa (1967) and Glypha (1977) are based upon it.
Split into simpler sentences: The response to Univers was immediate and positive; he claimed it became the model for his future typefaces. His slab serif designs Serifa (1967) and Glypha (1977) are directly based upon it.