I'm not sure anyone could get rich by doing this. It might be a good feature for new engines but I doubt most people would buy it for existing engines. I have an ASP two stroke, straight front mounted needle, and I know I would not spend money to change it.

Thunder Tiger, and some of the new OS engines, use angled needle valves to help with the issue of being close to the prop. Some use remote needles. My four stroke engines have the carb on the back.

Something I have seen. Most needles hve a little hole in the end for an extension, and a set screw to hold it in place. Drill the hole big enough to slide in a #2 screw and lock it in place with the set screw. Then use a ball driver or nutdriver (depending on screw type) to adjust. Costs a few minutes and the price of a screw.