If you want to retain the rear needle setup, use the standard rear NVA and the OS Nozzle 20-40FP-S, Tower stock number LXMU30 $6.29, OS part number 21381980 if it is still available.
For a front NVA setup, use the factory NVA 20-25FP-S, Tower stock number LXCR49 $13.49, OS part number 22311000.
There are now only two factory venturis—
FP 20/25 Venturi LXCW99 9.49 22312000
FP 40 Venturi LXCX05 11.99 23312000
The FP 20/25 venturi is 6.55mm ID, the FP 40 venturi is 7.1mm ID. This is the larger of the two that were supplier with the FP 35/40 when the factory supplied two venturis. It is also the venturi supplied with the 46LA-S. The smaller FP 35/40 venturi is 6.75mm (17/64") ID. I have reamed out FP 20/25 venturis to 6.75mm ID.
Depending on model weight, prop, etc, you will probably find that the LA will be happiest with the 6.75mm or the 7.1mm venturi. There is no single answer.