Well done for bringing it back from the dead Simon
one word, SUPERCHARGE! 
Dr. Eunos
Eunos R2 Limited Supercharged 1.8 `White Lightning`also a Eunos J2 Limited 1.8 very low milage.
Ex-`Member of The Glorious Green Gang
Organiser of annual `Nurburgring on a Budget` trip for MX5/Eunos only.
Disclaimer
Any work you do to your car is entirely your own responsibility. If in doubt, you should check technical advice with an independent , qualified person who has seen your car. Dr. Eunos of the MX5OC accepts no responsibility for any damage caused to your person or property as a result of you following or not following any advice offered on this forum.