Implicit Bifurcation of SSLIO for Joint Lives

[ETL]

I'm wondering any one has any insight into calculating the implicit bifurcation (annuity payment bifurcation) for SSLIOs when valued for a joint life such as a 50% J&S SSLIO.  Particularly, my team is debating whether or not it is appropriate to use the plan basis for the J&S conversion or the 417(e) basis.  When leveling both the participant and beneficiary benefit I can see a defense for either.  I can't seem to find any guidance on this so any input would be appreciated.  As a corollary, what are your thoughts when leveling just the participant benefit for something like a 50% J&S SSLIO?  We're thinking it makes the most sense to use the plan basis for such a case.

Thanks for the help!

[Effen]

Make sure you carefully review  1.417(e)-1(d)(6)(ii). There is a present value comparison/test is required under 417(e).