i have run 2.8 calipers with vented discs & 5.5j lotus rims but on capri struts. Maybe the position of the caliper is different on the cortina strut,some of the willwood calipers will only fit on certain wheels even though they are stated to fit 13" wheels. I was looking at some but you had to run them with 7jX13 wheels & as i was running 5.5j4spokes they would'nt fit. Ive heard of the lotus steals with the bigger rivetts on the inside of the wheel hitting the caliper? Sorry can't help any more than though