I am going to be ordering a triple weber setup for my L28.  First, my engine basic stats: L28 F54/Flattops, .040 bore,  E31 Head which is ported/etc, 500/300 cam, 6-1 header, pertronix igntition, etc.  My whole engine install thread here:   I've been running the round top SU's with SM needles.  They go lean up top despite the needles and repeatedly checking the floats/fuel delivery/etc.  Looking to go triples. The good news is my engine was built as a backup for a race