The 4-cyl pumps have one of those as well. I've wondered why they switched from the earlier style, which worked OK--at least as well as other SU pumps--to the square-body which, at least now, are ridiculously priced (some owners sub later, less expensive pumps).
Fuel pumps have bedeviled car owners forever. My dad's '55 T-Bird had a mechanical fuel pump which we could never get to be reliable (how simple can it be, it's driven by the cam???). It would intermittently stall the engine, and I could never figure out why (I finally guessed the inlet valve was sticking, but I'll never know for sure). I had a collection of 4 or 5 pumps, which looked good, but they all had problems. The car was 6V, and it was always a gamble to get it to start, after sitting for a few days, before the battery died. I even sprung for a 'Carter' brand which I figured, since it was a famous carburettor brand would be quality, but it was the same Chinese crap sold cheaper by other vendors. I sold the car to my BFF, and he finally bypassed it with an electrical pump. Modern pumps have issues too, and they're a real PITA because they're in the gas tank, which usually has to be pulled/dropped to replace the pump.