OP, both of these Offy intakes are awful performers
The open plenum 360 designs ruin the low speed throttle response on these intakes as well as all the single four barrel and dual four barrel intakes Offy made
The old and older two barrel carbs they where design for aren't worth using in todays world
the three bolt are for the early, pre 1958, Stromberg Carlson and older Holley two barrels, the four bolt patter is for the early low CFM flowing Rochester GM two barrel carbs, the later bigger ones where a liitle bit better but no where as good as the later Holley 2300 type two barrel carbs use on both Mopar 440 and Chevy 427 Corvettes starting in 1967 and the earlier 390 and 406 Fords back in 1961,1962 and 1963