The 38DGES will be synchronous. If it was jetted for a 2.2 it shouldn't be too far off the mark as far as jetting is concerned. The Weber will change the torque curve on the 2.4 so it will feel completely different to the EFI. Do everything you can to derestrict the intake manifold, even port match it to the head and clean up the ports. It will idle better and have better throttle response.