The Holley HP/XP carbs are great on paper, but I have seen and read so much about the problems they have.
I bought a QFT 750 for a mates 355, the ebay seller asked for our specs, and amazingly works perfect out of the box.
I pulled it down for inspection first, and to keep records, set throttles, set float levels, warm engine, set mixture etc.
You can get Quick Fuel metering blocks in black,
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