If you wish to consider a 3rd option, Aero Classic makes both a 9 row ($259.50) and a 10 row cooler ($262.95). Both available from Spruce. They are well built, and in my personal opinion, Aero Classic oil coolers seem to exhibit a little better efficiency at dissipating heat into the air flow than NDM coolers. They are lighter weight than a comparable NDM cooler too.
The RV8 in my avatar went thru 3 different oil coolers until we found one that both fits the mounting area physically and cools its heat-monster high-compression ECI Titan IO-360 engine in Texas summers.
First we used the NDM 7-row that came with the Vans kits. It proved to be grossly undersized. Next we used an overkill-sized Aero Classics 13-row and it cooled way too well, but also rubbed the inside of the cowling. I then bought a SW 10599R cooler and oil temps with it are perfect and the unit is a very good physical fit on the cyl 4 rear baffle in the RV8. This SW cooler just screams quality construction, but it was painful expensive. It's the "Cadillac" of oil coolers. In hindsight, we probably should've bought the 10-row Aero Classic cooler and saved over $300.
PS: Lostpilot28 here on the forums installed the 10-row Aero Classics cooler on his O-360 RV7 and reported successful results with both the cooling capacity plus physical mounting on the rear baffle of the engine.
