The manifold is correct & installed normal for a 300. Mine is a 310 with underslung exhaust. Your pic appears to be a 311, note the adjustable front & rear.
The sheet metal appears to have been cropped for access. Looks like a nice job too, I thought of doing similar to mine but am a near total loss re sheet metal work. The round nose sheet metal has to be removed to do almost anything in that cropped area, that is why so many of these tractor have missing and cut up sheet metal.
I have to unship my FEL to move the side sheetmetal away even a little bit. I tap the hyd filter cap, hook up & hang a 0-5 psi gauge near the dash and monitor the differential pressure across the element for a few days rather than all the hazzle to get at and pull the element for maintanence check. Course I do that on most filters out of shear laziness anyway.