that is a #14 casting allright. Not to worry if its ok now just take care not to overheat it and it should last a long time.
Right, #1 is the frontmost cylinder.
Remove the intake manifold with the lines still attached underneath. You will still need new plastic clips as they tend to break getting them off.
You will need a ball head hex driver or a universal jointed driver. I can't remember which, 4mm or 6mm? Wiha makes a clever hex key with a tiny c-clip incorporated in it that holds the socket head screw so it won't fall off, a nice tool to have on this job. After the manifold is off, stuff socks or something into the head to prevent letting debris into the openings.
Getting all the air out of the injector lines will arise, its a frequent problem and there have been numerous posts on this but leave the lines loose at the INjectors and crank about 15 seconds, with the accelerator pedal down, pause a while to let the starter motor cool the repeat this until fuel is running onto the block, then tighten the nuts at the injectors and continue cranking until it runs.
There are mechanics that will replace GP's with the manifold inplace. My hands are too large and I avoid self inflicted pain so I remove the manifold. Besides you probably need to clean the crossover and manifold crud inside that tends to build up (esp if egr is operational!)

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!