What do you want from the engine?

The single Weber manifold is capable of much more performance than the twin SU manifold, but the 32/36 DGV is a smallish carburettor that was designed primarily as an economy/emissions piece & it is by far the hardest carburettor there ever was to jet. Because the 32/36 actually only flows the same amount of air as a HIF6, it won't produce any more power than twin SU's & it never will match the fuel economy of Twin SU's.

Want to use the single Weber manifold for performance? Then look at the carb Volvo actually sold with the single Weber manifold: a 36/36 DCD or you could use something bigger like a 500cfm 2bbl Holley. Those will beat twin SU's for power when used with a bigger cam & hopefully some cylinder head work.

(FYI: The Volvo GT kit consisted of the DCD Weber, ported E head & K cam & it produced the same torque + 10 more DIN HP than a B20E.)

Want a nostalgic look & maximum fuel economy? Twin HS6 SU's + at least a K cam with KD or KN needles & up the compression a bit. I'd use a late B20A/B head from somewhere other than the USA & do a little work to it. If you get lucky and find two good HIF6 SU's, then more headwork, dual springs & at least a D cam with BBB needles & you will have economy with something approaching the GT kit (depends on how good the head work is)

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Three 164's, Two 144's, One 142 & a partridge in a pear tree.