I have never run 200 with iron heads, high compression, and a big cam. With fresh ambient air going down the carb, you should be OK.
I am very keen to change your mechanical timing to 18 in the D, and to delay your all-in timing to nearer 32*@3600rpm. That would be 63mph. If that cures your detonation, I would
sneak up on the timing,by first moving the rpm down 200rpm, to 3400, and retest. Then 34*@3400. But if still detonation-free there, I think I would stop the hunt. With 4.56s, IMO, there's no point on the street to strive for the limit. Anytime you nail it, she will spool up quick, and you won't miss a few horsepower; let it go. Top of second gear will get you 60mph in 6 seconds or less, so relatively speaking, loosing 5 or even 10 horsepower is as small deal. Whereas to gamble your engine for 2*or 200rpm, and loosing it, is a really BIG deal. Sometimes less is more.
Don't get hung up on the shape of the timing curve. Just get it slowed down for now. Put the stiffest shortest springs in there you got and buzz it up till it stops advancing. Then crank it back to 32*.If it comes all-in before 3600 you will need stiffer springs or lighter weights. Do what you gotta do to delay the all-in to at least 3400; at least!
If factory springs fit in your Distributor, I very highly recommend a two-stage curve. This requires one spring to have a long loop in it and to be very stiff.This guy will slow the second part of the curve right down, and since it does nothing in the first part, the curve down there will be very fast, so put the shortest stiffest spring you got on the other posts. So now your job is to set the changeover part of the curve as low as you can without getting detonation. Then the second part will/should keep it out of detonation.
But if factory springs do NOT fit in your D, then just slow it down as best as you can and delay the all-in as earlier described.
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My kink/bend ended up at 2800; and the second and total part is all-in at 3400. I have 20* in the D, and run 14 initial, for a total of 34* possible. The curve starts advancing at about 900 rpm .This keeps my aluminum headed-combo out of detonation and I can run 87E10 full-time, with 185psi cranking cylinder pressure.
I could and have, run a faster first part, but I didn't feel any gains on the street in my combo, so I took the safer route, with the idea that I might work on the curve at a later date. I never did bother ....... cuz I never needed more power,lol.
My cooling system runs at 205*F full-time, within a few degrees.
I run the next size smaller Hughes cam;
HE3037AL; 276/286/110/61overlap and 230/
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HE3844AL: 286/290/108/72overlap and 238/
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With yours in at 106 and mine in at 108 almost all the difference is in the overlap
