In the metal-organic perovskite copper guanidinium formate, correlated Jahn-Teller distortion gives rise to a 1D magnetic structure made up of Heisenberg antiferromagnetic chains. We have previously shown that muSR experiments are capable of probing the correlation length in these chains. However, at least six muon sites are resolvable, and this complexity prevented us from measuring correlation lengths quantitatively. We therefore propose here angle-resolved muSR experiments in order to assign a local field orientation to each muon site, and hence to measure the correlation length directly as a function of temperature. Our results will be relevant to developing new materials for applications and fundamental physics as well as demonstrating a new way of extracting useful magnetic information from muSR data.