No way to be able to tell that. 4-AcO-DMT could just be as safe. Hell, it could be safer. It's not out of the realm of possibility for me because 4-AcO-DMT and the AcO tryptamines in general FEEL less hard on the body than their 4-HO counterparts. Griggs is reported to have died from around a gram of pure psilocin. Though it could be fabricated I think.
I've heard this about griggs too, and was always skeptical.......Ive also heard (and talked to some) that he actually overdosed on PCP, which was indeed making its way thru the brotherhood at the time, being called both psilocin, pislocybin, and mescaline. PCP does make alot more sense to me.
And, for what it is worth, ( a vague comparison), the LD50 for psilocybin in rats is 285mg per kg, 280mg/kg for mice. And that is intravenously

!! much higher safety margin than most other psychs. (from Psychotropic Drugs and Related Compounds, NIMH Edition)
OP- very glad you are OK. Sounds like you had a beautiful *peak* experience. cheers.