Post #1 is full of info
but the most important info is missing. How much cylinder pressure is that engine running and at what altitude is it operating?
KB107s are flat-tops and in a 360 sit down in the hole. X-heads are open chamber items. The 262 has a very early ICA. But unless you have done a lot of machining, the engine should not be detonating. Well yeah your timing is all in a little early, but there is something you haven't told us,namely the cylinder pressure..
A little detective work,; with no machining, this is a 9.5 engine. the 262,in at 106 makes an ICA of 59*. This conspires to make a Dcr of 7.9 and cylinder pressure of 158 at sealevel;just about perfect,for iron heads.And should not require 93.
Soooooooooo, what's your pressure.
Three things lead to detonation; too much heat, and too much heat, and too much heat; for the fuel.The heat can come from excessive pressure,too-early timing, a hot-running cooling system,hot-air intake,hot spots in the chambers,restrictive exhaust, or lean AFRs.
Did I miss anything?
Oh yeah, too high a load.As in secondaries coming in too soon.
-If it detonates after 4000, you can probably rule out your timing. That combo should run full-timing ok at 180*engine temp.If you have a scoop, you can rule out hot-air. If you have headers and duals exhaust looks covered. That leaves just; pressure,hot-spots and AFR.
-But if it detonates right from the get-go, Perhaps the secondaries are coming in too early,or the exhaust is not getting out,or as you have already surmised, the timing is all-in too early.
-If it detonates between say 3000 and 4000, then cutting back the timing should help.But you tried that and even at 30* it is still detonating.
Soooooo, what's the pressure?
-If the pressure is below 160psi,and timing is under 36*,and it still detonates after 4000,then you have three choices,I think; Hot spots in the chambers,Lean AFRs, or hot inducted air.
It's all about too-much heat,or too much load.
Ok here's a wild card; the heat could be from something in the chamber that should not be in there,lol. Like exhaust,engine oil, something in the gas,or not in the gas that should be in, or a gasket overhanging the top of the bore,or plain old carbon. I would clean out the chambers and start over.
-If the pressure is over 160, you are gonna have to be sharp on the tune.
I like this combo;it should make a ton of torque, and be a pleasure to cruise around in. I also see lots of tire-smoke
