The Rover V8 is an old design so works best with 20/50 in my experience. The design is noted for being high volume/low pressure, and the standard of the day where there was a pressure gauge, was not to have a warning light. My V8 used to run a whiff over 30psi at 3k rpm, but would be low at tickover. To be honest I can't now remember what that was. It was the basic cover with distributor drive. In 1972/3. MG were inundated with complaints from MGB ovners who had bought a V8 and thought the pressure wasn't good enough (compared to the 1800). The solution was to fit an uprated relief valve which upped the pressure from high 20's to low 30's psi. There was also available an adaptor plate which fitted under the pump cover, and accepted deeper pump vanes to provide more capacity, but I didn't try one. The MGBV8 had a remote filter, which is why the pump had a cover plate. There will be pressure at tickover, start by bleeding the pipe at the gauge end!
