Anyone know a US part number?
I can't read it on the filter on the
car. TIA.

 

... is SPI your Classic?

Fram has a #PH966B spin-on and
Purolator has L10028

... any thing that would fit an Austin America or MG Midget would fit '70's Minis as well. (and I still have a drawer full of Unipart filters from England if you can't find anything else).

 

be care full not to get a mpi filter they are a diffrent fitment and depending on the year of your car (1990- to about 1996 for single point) you will need to get the correct fitment.