I’ve never heard of the model B1+. I think the only available models are RPi 1 A/B, A+/B+ and RPi 2. From your description it looks like you have the RPi B. Note that OSPi 1.42+ does NOT work with the original A and B models — it only works with A+/B+ or RPi 2. Because the pins are backward compatible, you can still use ribbon cables to connect RPi B with the pin headers on OSPi. However, honestly I think the easiest solution is to just buy a A+, which is the cheapest RPi and it would work nicely with OSPi 1.42+.