Gray smoke with strong fuel smell is usually retarded timing. If you advance it, and it either becomes too noisy (Diesel rattle) to clear up the smoke, or doesn't help much or at all, the IP is suspect. (Too) retarded timing effectively lowers the compression ratio, causing late, incomplete combustion and unburnt fuel exiting the exhaust (smokes off in the hot pipe). It's simple to test retarded timing on a warm engine by powering the HPCA (apply 12V to the spade, after the engine is up to operating temp), which advances the timing a few degrees. Diesel rattle should increase and smoke should clear. It is also important to test it to ensure it works. If it is either stuck advanced, or doesn't engage, damage can occur if it suddenly decides to work. The burned glow plug could simply have been a bad plug. I've seen more than a few over the years, of all brands. A bad IP (uneven timing) can also burn individual plugs (as well as damage cylinders/pistons). With your compression test values, it's unlikely any permanent damage is done. Running the engine for an extended period with a failed lift pump can damage the IP, as well.