Very nice!
That ejection port is what I would consider to already be lowered. The original 1911 port barely extended into the flat of the slide and even those can be reliable for ejection, they just leave a dent on the case mouth. Flaring the back edge of the port can help in preventing the cases from getting dented in the case head area, but beyond that, the flare is not necessary.
Most factory produced 1911's have a sloppy fit to the firing pin retainer and extractor. This allows the extractor to rotate slightly, which can affect extraction and ejection. A 1911 that ejects brass over a wide area is almost certain to have an extractor that is rotating. A fitted firing pin retainer and possibly a new extractor are the answers to this problem.
1911 feed reliability horror stories often come from crummy magazines. The 1911 needs a quality magazine, held to fairly tight specifications, and the magazine needs to be held at the correct height within the receiver. I have experience with an old Thompson Auto-Ordnance 1911 (1980's production) that had receiver with a poorly positioned magazine catch hole. It worked if you applied pressure to the bottom of the magazine when firing, but without upward pressure, a feed jam was likely to occur.
Poorly made magazines are the bane of the 1911. Gun shows are often filled with cheap knock off mags, sometimes in military style wrapping paper and with a NSN number on the base plate. A 1911 magazine that costs you only $5 is going to give you a $5 performance. You get what you pay for. For reliable and affordable magazines, genuine Colt magazines are good as are Springfield Armory, Mec-Gar, Metalform and Checkmate. There are others, but they will cost more.
If you want to know a whole lot more about 1911 magazine identification, check out this thread over at the m1911.org Forums.
1911 Magazine Identification