Go for the Mazda mx5 1.8 fuel injected engine. My son has one in his Eunos. Goes like the wind and flexible too. Fit a decent air filter with a cold air supply. Have a look at the link below. Peter.
https://www.evo.co.uk/mazda/mx-5/153...mazda-mx-5-mk1
P S Lots of good spares available at mx5 parts too. Peter.