Suzuki 2 Strokes

I purchased a 73 GT550 not so long ago. What I didn't know at the time (due to my unfamiliarity with these bikes), is it has a later model engine in it. Somewhere along the line, it was changed I assume. I'd like to at least have the year correct jugs/head/scoop on it. I have already purchased a scoop and head, but I am wondering if there are any differences in the cylinders between the two styles of engine (72/3 vs 74 up). I know the fins are longer on the earlier bikes and the carb setup is totally different. I have the older carbs, so that keeps me from hunting those down.

Has anyone mated the old jugs with a newer lower? Did Suzuki change any of the mating between engine styles?

Thanks.

I have 72 cylinders on a 1975 engine with no problems whatsoever. Keep in mind a different shape base gasket is needed (old style) as there is different porting
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As far as I know, the stud spacing on the cases for mounting the jugs never changed on the 380 or 550.

In Europe the 'A' models got SCEM-coated (Nikasil) bores and extra transfer ports, but they didn't make it to the US market as far as anyone knows.