The Hunter MP and MP SR’s screw onto a standard 1/2" male NPT (they are a standard 1/2" female NPT), since most sprinkler bodies are 1/2" male NPT they should screw onto your rainbird sprinkler heads.
However, the MP’s need to be pressure regulated at 40 psi (or possibly 30 psi) to get optimum performance and a consistant throw distance. This is best accomplished by switching out your sprinkler bodies with pressure regulated sprinkler bodies (30 or 40 psi). Sprinkler bodies with a check value (either pre-installed or field-installed) will give additional water saving benefits for down-hill sprinklers. Rain bird does sell a similar product (both the pressure regulated bodies and rotator heads), but I’m a Hunter fan.
The MP Rotator heads can be adjusted down by 25%. So, the SR’s would have a throw distance of 8’ - 10’ at 40 psi, 6’ - 8’ at 30 psi, and 10’ -12’ if a non-pressure regulated sprinkler body was used and the static pressure was ~ 55 psi. Note: the SR’s have a higher precipate rate of ~0.8 in/hr vs. the MP standard precipate rate of ~0.4 in/hr, so they are not suggested to be used in the same zone as the MP rotators, but can be with an adjusted schedule time (according to the Hunter tech I called).
The Hunter website has lots of videos and spec tables to help you determine just what you need.