I think that the basic idea to improving this track is just to simplify it. I don’t see the need for all the square corners that don’t lead to anything but more square corners. So basically, treat it like a road course, not a street circuit.
Thats the best that I could do. The first corner would be really fast, and there would need to be a major overhaul of that whole section of the track, but it would be interesting, seeing as its almost a double-apex left hander, the “straight” between the two apexes being a constant curve. This could definitely make the run up to turn 4 a better passing opportunity, seeing as those corners become a Monza-esque momentum section, leading to higher speeds, and easier passing.
The biggest problem here is, as @necrodethmortem pointed out, the stupid chicane that is necessary coming off of St. Andrews Rd. and onto Connaught Dr. Still, the faster corners just before the chicane allow higher speed into the chicane, possibly creating passing possibilities, and definitely making the chicane a more critical part of the track.
And the last problem is the fact that this layout gets rid of the Grandstand tunnel, which is dissapointing because those are permanent grandstands, and I’m sure they’d hate to get rid of them. Also, the speed being carried into the corner that peels off of Raffles Ave and onto the permanent track would be very high, seeing as its coming off the straight, which might necessitate another one of those stupid chicanes. Oh well, I still think this would be the best option for F1 cars.