Not sure if it's still the same these days, but in SA "banding" was illegal, i.e. you couldn't widen steel heels by putting a steel band in the middle of them which was then welded on each side. But one single weld was ok, so the use of spun halves was legal.

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Slide
1965 Mini Van (1360)
1970 Mk2 Cooper S (1310)
1978 Rover SD1 V8 (4.6)
1996 Land Rover Discovery V8 (4.0)

Back then I used to do them for Parramatta speed Shop. The well on an S wheel is 1/8" smaller than a 3.50B Mini outer rim (made in Oz).
After splitting the outer rim I had to roll it down in the lathe to match the S one.
Welds were done with stick electrode, a pinhole didn't matter much as all tyres then had tubes.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.