Dome-top SU carbs were used on factory Datsun motors. Four different Datsun models found in the US came stock with dome-top SU carbs:

• The '65-'68 411 SSS used 38mm dome-top Hitachi-SUs,
• The '65-'70 1600 Roadsters used 38mm dome-top Hitachi-SUs,
• The '67-'70 2000 Roadsters used the 46mm dome-top Hitachi-SUs,
• The '70-'73 240Zs used (different) 46mm dome-top Hitachi-SUs. Click here for information on adapting the Z car SUs to a 4cyl L-series motor.

Because the cars above were imported into the States with SUs, there are sources for parts and knowledge to help you get your setup running on your 510. As I said before, many 510 owners use the flat-top carbs.