Hi, hoping I can get some help confirming what I believe I have. Please correct me if I am wrong, and provide any additional info from your breadth of knowledge. Apologies for the lengthy missive but trying to provide a such info as possible.

1990 Japan spec Mini Mayfair 1000, std, rhd. Resprayed in original British Racing Green (Paint Code HNA Trim Code LOY) with White roof, looks rock solid save for relatively minor rust bottom inside of door skins. Centered oval gauge cluster with functioning speedo showing 88608 KM. A few less common features like antenna in fender and wing mount mirrors. Front discs are 4 pot opposed calipers. VIN SAXXL2S1N20473954, body # on smash panel 820S 8655 42A. Also has factory electric auxiliary fan in fender, run by aftermarket switch in small dash switch panel, but there is a sensor in a bung in a pipe spliced into the lower rad hose that I think might be for the fan. Also has remnant of what appears to have been a white nylon/plastic fuel return line that's capped off in the engine compartment, and capped of below the floor from where it goes into the very top of the fuel tank through a one way check valve that only allows fuel/vapour to pass into the fuel tank. Possible just a vapour recovery system?

Wondering if it could have been early SPI, though I thought that started in 1991. It has a catalytic converter and the exhaust pipe downstream of the converter has a plugged bung, like an O2 sensor location. Also there is a red indicator warning light in the lower right dash panel with "EXH" lettered on the face of the indicator light.

It is a John Cooper Garage Anniversary Model Conversion By "Garage Morris GM Company LTD. Yagumo, Meguro-KU, Tokyo 152". Mini does not look like the Rover 30th Anniversary Model so could it be a John Cooper 30th Anniversary model?

Type SAXXL2S1N20473934
Chassis 99X (0/U) 9 (0/U) BGM0117UL
(In parenthesis above poor stamping with only bottom of placement showing
so not sure if those spots are "0's" or "U's")
Japanese VIN 99X 17883 AR stamped in floor of boot.

Cylinder head and block certainly similarly aged and the same faded yellowish color. Head is a 'CAM 4810' casting, unleaded as I understand, and on the top machined surface stamped "COOPER" and "8169", this is at the rear of the head and not by the thermostat.
As to the block, on machined deck protrusion near T'stat is stamped "H66", didn't think Cooper Conversions involved block work but wonder why it's stamped? Block # 99HE 113508, which I believe is a low compression block, casting WFM 1026/4 NW.
"COOPER" stamped into intake manifold and sporting a pair of 1 1/4" SU carbs.

Other possible Cooper accoutrements are "Mini" badges front and rear, heavy polished metal dipstick pull, steel spoke steering wheel with JOHN COOPER cut/recessed into steering wheel spoke that's pointing towards the 2 o'clock position, tach in front of steering wheel, and an original Pioneer AM/FM/CD stereo model # DEH-P500 complete with Japanese manual for it, with a Japanese CD still in the unit.

Other than one split and one close to splitting CV boot, she's a good runner. The suspension has had serious upgrades with the rubber cones all replaced with coil springs, Hi/LO set ups front and rear, and dial adjustable shocks. Running on 12" Revolution black 4 spoke alloy wheels. Front seats are nice buckets with understandable wear and tear but comfortable, stock gray upholstered rears seats.
Haven't done a warm compression test yet, but cold, with not very fast cranking speed, I am getting 150 psi +/- about 2-3 psi. across the board.

Thanks for looking.