Using carburetor needle valve assembly?

If you made an appropriately sized venturi then of course, especially if you run tank pressure.

Essentially, the LA-S series were designed using the remote needle. It was attached to the backplate. This was a poor design leading to many problems. The earlier LA-S engines used the metal bracket which held the needle and then screwed to the backplate. The later versions used a backplate with the needle valve arm assembly molded into it. It would break, create leaks and havoc. I would razor saw the arm off before I ever ran the engine and fabricated my own aluminum bracket to hold the needle valve. The steel bracket and the plastic version held the needle valve assembly perpendicular to it. Another bad design, if the model goes in the needle breaks off. Just like in combat, keep the needle assembly parallel to the crankshaft.

I use bladder, there are certain OS needles that work well, and others not so well. For the most part, many have been discontinued. The OS #1A was our r/c needle valve of choice. One thing I noted is that when you would buy many of the same items from Tower Hobbies, they would discontinue it quickly which is exactly what happened. They did it with the Tower .40 backplates, FP .25 backplates, and the needles I mentioned when everyone would purchase them in bulk. The LA series all used plastic backplates and the Tower and FP versions fit the LA so many purchased them. The OS #2A was used on larger engines .25-.40 and while this needle worked, it didn't have the finer adjustment of the #1A due to a coarse thread.

OS still offers the LA series venturi, which fits the FP. This would require the stock OS .20-.46 needle valve assembly or the spraybar for the LA series which is a nipple on one side and a nut on the opposing.

As mentioned, your flying style is going to dictate the size. Personally I use bladders and I opt for larger venturi's. The large OS size I use this with no spraybar through the venturi. This probably wouldn't work running a tank due to the spraybar itself being around .157 ". The OS Venturi's are labeled S & L. S being about .265" and the large .280".

So the long and short of it is yes it works.