Where the heatsinks aligned like this = or this +?
If they were like this = I was going to build a wind tunnel and put a 120mm fan at one end and blow air over both heatsinks.
But last I saw Marto changed the heatsink design to +. For that configuration I was going to put 2x 43cfm 92mm fans on top with cable ties.
The heatsink is like this

Yeah the heatsink air flows are in a cross + so you cannot use a wind tunnel to cover both heatsinks with a big fan.
Can you measure the length of the heatsink and see if it's 184mm long.
2x 92mm fans on the top was my next idea, depends on length of heatsink though.