New replacement air filters for the 2 litre cars can be the K&N part number E4530, (it’s a tight fit, but it does fit! – Adrian Berry)
K&N Filters are available from a number of suppliers.
Specifications: 5-7/8″OD, 3-1/8″ID, 3-3/8″H
K&N Small Engine and Light Industrial Replacement Air Filters – K&N manufactures many direct replacement elements
for small industrial engines, utility lawn and garden units, air compressors, generators, chain saws, etc.