These are belt drive so no idea how much GPM, but if you mean RPM I think your safe anywhere from 1,000 to 4,000.
most handy folk have been able to use the hitches I have and make them work. Few guys bought a subframe form theirs and it was around $500 new.
I am not expereienced at fitting to other models. I put my effort into making them fit the Simplicity sovereigns as that is the model I have. I am sure with basic skills one could make these work as is and spend no extra $$$. I saw a youtube video of a berco on a case, and the blower was near same as mine.