Flexilite has long sold a dual-fan plastic shroud that fits a stock rad core or an aluminum rad upgrade. I think Maradyne sells virtually the same rig thru Pantera vendors. Fans are not normally needed at road speeds over about 35 mph, only around town. Biggest problem I found, aside from initially using too-small (10" OD) fans is, my home-made aluminum shroud restricted airflow thru the rad at very high speeds.
In a test on Judy's and my favorite 70-mile straight desert highway at a sustained speed of 150 mph for 10 minutes, my too-small shroud consistently caused water temps to slowly climb towards 250F (from 210F) until we slowed down. Then temps returned to normal. Using a Flexilite plastic shroud with bigger 12" fans & larger openings in a later test run, that didn't happen @ 150.
Some OEM rad shrouds use small flexible rubber blow-aside flaps to compensate for higher speed air flows. Honda Civics are an example. At low speeds, fan suction keeps the flaps sealed to the shroud, but high speed ram-air blows them open as req'd. Owners would have to fabricate such flaps for a Pantera or Mangusta shroud. I've not done this personally as I seldom exceed 140 mph anymore, at my age.