I havent had a lot of experience with the rover/suzuki engines, does it fire if you put a bit of fuel down the carb? With these I have found the easiest way to get the carby off without having dramas with the linkages is to take the two nuts that hold the air filter housing on, tighten them against each other on the studs sticking out and unscrew the carb mounting studs out of the block.
Personally I would say there is a minor blockage there somewhere, it may be worth one last time pulling the carb down and blowing everything out with compressed air...
