If you are talking about a piped screamer, approach it like you would if you're tuning a diesel...start with a compression that barely runs and subtract shims from there. If you aren't happy with the expected results, then raise the liner a couple thousandths. Always monitor the glow plugs, there is no excuse for obliterating them on every run, but a well tuned engine on high nitro will consume a plug about every run. With 30% or less nitro you should get several runs per plug. Weak engine mounts will eat plugs, too.
Engines with low nitro chambers shouldn't be run with much higher nitro than what is called out.