Any one have any suggestions as to what needle and spray bar will fit an OS LA 10 engine?
        Thanks,     

If you have access to a lathe, you might be able to turn down one for an OS15 or 25.  Then use nylon spacer blocks to center the spray bar holes in the venturi.

If you can't fit the threaded part of the spraybar in the crank case holes then you're already shot out of the water, unless you want to hack up your crank case.  But if you have a spraybar where the threaded portion will fit but not the smooth portion, it should be reasonable to turn it down.