StaufferV8 offers a conversion kit to install a Ford Flathead V8 into a Ford 9N, 2N, and 8N tractors. The kit works with any Flathead from a 1948-1953 Ford/Mercury truck or 1949-1953 Ford/Mercury car and large spline (10 or 11-inch) clutch and Flathead flywheel pressure plate. Update 7-28-2019: The kit is sold by Awesome Henry.
Source: StaufferV8 (site no longer active) via Jalopnik