The MGA Twin Cam pin drive rear axle hub installs very similar to a wire wheel spline drive hub hub. Expect the force required to be around 10 tons, slightly higher for disassembly, maybe a bit less for installation. Ian Renshaw reported success for assembly with a 12 ton press. Press the parts together until the outboard end of the half shaft is very near flush with the shoulder in the hub, but definitely not above flush. there is a Welsh Plug needing to be installed here to prevent oil from leaking out through the spline joint.

Photo compliments of Ian Renshaw