I had an old mitsubishi lancer ('89?) that refused to rev very high when cold, almost like it choked up, until I set the valve gaps properly. Then it was just fine. Something else to think about.
Matt, I've adjusted the valves with a dial indicator and i'm pretty sure they are set right, it idles nicely and has factory compression, you can see how i made the tool and set the valves on this thread : https://www.hobby-machinist.com/thr...did-you-make-in-your-shop-today.67833/page-39Or refit the car with a 1 litre 3 cylinder turbo from a Ford Fiesta