one of the more important consequence for having a deeper tank against a wider tank is oxygen exchange. computing the water volume in proportion to the area of water surface you will need lots of water motion to sustain a good oxygen supply in your water.
i also think a single eheim 1264 is not enough for the size of your tank; neither a single wavemaker. if you are planning to keep corals, you will need to consider the proper flow and turnover rate of your water for good filtration. just to give you an idea, i am running 1 x iwaki md70 and 1 x iwaki md30 as return pumps; 2 x vortech mp40, 2 x tunze 6060, 1 x tunze 6080, 1 x tunze 6100 and 1 x tunze 6130 for my 6ft L x 3ft W x 20" height sps tank.... with all these equipment, i still find water movement is not enough after liverocks are introduced.
better do things proper from the start as it might be more costly and troublesome to rectify mistakes.