*might* is the operative word for the move of the early 1.8 cars to ES.

Beyond that though... What tires are you running? If you're buddy was on race tires and you weren't, that'd be a lot of the "tight" feeling with the car. They don't roll, and they react VERY quickly to car inputs.

Shocks would be a GOOD idea on any car.

springs...i'd leave them. 2 schools of thought on used springs.

a) older means they droop, so your car is actually lower
b) older means they lose some stiffness...im not that convinced, but on a stock car, the shocks are doing a lot of work, so i'd be doing that and a front bar on a miata......unless you're still on street tires.

if you're still on street tires... you could show up at a local with cams and a built motor, and personally, I wouldn't care if you wanted to run ES.