[Killa B]

So I rebuilt my 89 N/A a while back the head was torqued wrong due to all-data listing for spec so the head warped and I had to get it machined again. Ever since the rebuild it was hard to get the spark advance just right and it became more difficult after the head was machined the second time. I don't know exactly what was taken off but someone had told me once a head is Machined the spark advance becomes a whe lot more precise to set perfectly I was wondering if anyone knew the best way to set it to the exact potion and yes I have replaced the rotor button and cap spark plugs and wires I'm running NGK laser platinum twin tip plugs now. Any help would be appreciated!! Thanks.