I went with -20 An fittings on my radiator only because my car even though almost 1000 H.P. on Motor is still street driven. But my Mezeire water pump is within the aluminum housing & not mounted to the rad like you are doing.

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1963 Belvedere 440 Max Wedge Tribute
1970 Charger R/T S.E. 440 Six Pack
1970 Challenger R/T, 528 Hemi
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner 383
1974 Chrysler New Yorker 440
1996 2500 RAM 488 V-10 4X4
2004 3500 Dually Cummins 4x4
2012 Challenger R/T Classic.