MG Car Repair: 1500 series engine block, nash metropolitan, moss motors

Question
I am a owner of a 1960 Nash Metropolitan that was fully restored about 15 years ago. Well I just recently I took the engine to a shop and had it rebuilt and I put it back in the Metropolitan.Well I ran in a major problem. The adapter that screws into the block that the oil filter oil return line connects to cracked. I called several Metropolitan part suppliers and they all said the Metropolitans all came with one size so I don't know where I could find this part.The size I need is 1/2" Diameter where it screws in the block and the other end is about 3/4" Diameter where the oil return pipe screws to.The part that was suppose to be there stock size was 3/4" Diameter where it screws in the block and 3/4" where the oil return connects to.My engine Block has 1500 written on it But the adapter hole is 1/2" not 3/4".

 It would be very much appreciated if you could tell me any info on how to get this right size adapter.I have spent a lot of money on this car and know it is just sitting in the garage.
Thanks William Hayes

Answer
HI William.  This is a bit outside my area of expertise, but I seem to remember the Metropolitan had basically the same engine as an MGA or Z Magnette.  The adapter you need is probably threaded 1/2 inch BSP (British Standard Pipe) at one end and 3/8 BSP at the other end.  Try a British car specialist such as Moss Motors.  Or a supplier of oil coolers.  In the UK I would ask Flexolite, or I would go to Europa Spares.  

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If you are still stuck, get back to me.  I have found a used one in my parts bin.