You can't convert SARA to PIONA, for one reason the Aliphatics are not separated into normal or branched alkanes. The analytic techniques are different, I would suggest it is not worth attempting because the analyses are cheap and there is little point. What are you hoping to achieve?

Thanks for your answer. What I have now is PIONA crude oil analysis. I am just curious if we can extend LCMS results to PIONA or SARA and vice versa. Thanks.

There is an article "Relationship of the aromatic structural types in vacuum gas oil to empirical correlations based on bulk properties" which implies there is a relationship from LCMS.

Reference  http://www.tandfonline.com/doi/full/10.1080/10916466.2016.1170845

Thank you so much.