The opportunity for a bit of confusion is substantial.

-- The main oil pressure relief valve in the iron block engines is in the block (item #15 above).
-- The main oil pressure relief valve in the aluminum block engines is in the oil pump.
-- There is no main oil pressure relief in the block of the aluminum engines.
-- Both iron and aluminum block engines do have a cooler bypass valve in the block (item #16 above).
-- USA aluminum block 107 engines were not equipped with oil coolers. (A sufficient number of both 126 and 107 cars came to the US as gray-market cars that a few of them may have had coolers.)
-- The plugged oil return (cooled oil) port, circled in yellow, in the picture above enters the filter element on the outside (normal flow).
-- The oil circuit for the 107 does not incorporate a thermostat.
-- The oil circuit for the 126 does incorporate a thermostat.