kevin wrote:
Who is going to do the work and how???

I will be. But that doesn't tell you much, since you don't know my
work, past experience, training etc. I do happen to be an engineer by
training, sort of, which still tells you nothing, because there are a
lot of mechanically disinclined engineers out there.

You missed my point completely, methinks, by eliding the quoted
material---the point is you claimed it's not a critical support (and
therefore isn't worthy of a professional opinion) because the building
is unoccupied and nobody is either in or under it but by the same token
are planning work in the basement. I was asking (the rhetorical
question of) "if nobody is there to potentially get hurt when your
makeshift beam/truss fails, how is the work going to get done?" to try
to make the point it isn't such a throwaway question as you seem to
want to make it.

I'm sticking with if you don't have specific experience appropriate to
the task, best not try something particularly exotic and as someone
else noted, the difference in some minimal material cost now could
easily save much later.

Perhaps an alternative is a combination of both--use 3 or 4 or so 2x8
and add a small truss-like structure above to add some additional
stiffness. But, I'd surely want to look at the overall structural
stability and load transferral some before committing to knocking out
the supporting wall.