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 R$\mathrm{_{FeII}}$, 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 (T$\mathrm{_{BBB}}$) defined by the Big Blue Bump on the Spectral Energy Distribution. We select five extreme sources that have R$\mathrm{_{FeII}} \geq $ 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 R$\mathrm{_{FeII}}$ for this object.