  The work initially started as a test to retrace the Shen & Ho (2014) Quasar
Main Sequence diagram where they (and references therein) claimed that the
parameter RFeII, which defines the Eigenvector 1 (EV1) is driven by the
Eddington ratio alone. We subsequently construct a refined (error and redshift
limited) sample from the original Shen et. al (2011) QSO catalogue. Based on
our hypothesis - the main driver of the Quasar Main Sequence is the maximum of
the accretion disk temperature defined by the Big Blue Bump on the Spectral
Energy Distribution. We select five extreme sources that have RFeII >= 4.0 and
use the SED modelling code CIGALE to fit the multi-band photometric data for
these sources. Incorporating the prescription for broad emission-line species
dependent virial factors, we derive the black hole masses for the entire
Shen+11 catalogue and compare their distribution with the black hole masses in
the original catalogue. Here, we show the results of our analysis for one of
the 5 extreme sources, SDSSJ082358.30+213545.2. We also show the detailed
modelling, including the Fe II pseudo-continuum to estimate and compare the
value of RFeII for this object.
