Well at least he was specific.
This is a tough and messy highly specialist oriented nuclear physics problem that I am not in the position to help you with really. But I do know a little bit of the game they play b/c the particular interaction is known to be fruitful in principle for experimental data on the strong interaction (dont ask me for specifics).
The pion and protons fundamentally are composite particle, and there will be electromagnetic interactions as well as strong interactions taking place. Typically the game is to guess appropriate form factors, and run distorted wave born approximation algorithms on them etc.
Anyway, youu have a spin 0 and spin 1/2 target so you will have several polarization observables (from the flip and antispin flip amplitudes)+ unpolarized ones. You are also working with low energies so there is going to be residual complications on the compositness of the target (say a heavy nucleus with a lot of protons floating around on the outer orbitals).
You will need to consult a specialist for more details, say at your local university.. I very much doubt that by chance someone here knows the details explicitly.
