Spark plug question

[76bonanza]

I just installed headers. How much clearence should I have for my plug wire boots some are pretty close? I have taylor spiro pro wires.

I use ngk 6630 right now wondering about the accel header plugs? Anyone use them? And anyone know what number accel is in the same heat range as the ngk?

And speaking about the ngks are the 6630's the right heat range for a stock 350 with headers and an msd probillit hei dist.?

Thanks