Tom, you probably don't need to replace ALL of the tubes/seals.  I sell these
spring loded tubes with the seals for $19.  At my calculations if you had to
replace all 8 this would only come to $152 (pricey but not $400).

If you are going to redo the heads and the tube seals at the same time, I
would recommend buying a complete engine gasket kit which I sell for $99 and
is German.  That would give you all the seals you need including both head
gaskets and you would also have extra gaskets left over in case of another
leak in the future.

Finally I would check the tube that goes from your crankcase ventilation
tower (that black tower looking thing on top of the motor) to the intake
boot.  Many times these get pinched and oil starts coming out around all
kinds of seals.  Most of the time if you fix this problem the oil leaks go
away.
Hope this helps you.
Ken Wilford
Van-Again
John 3:16