Well, I have alittle more information, ideas.
The steel I have is 1045 which suposedly gives 82KSI (82,000 KSI ?)
Also, I spoke with a blackpowder rifle barrel builder, who thinks I am plenty safe a 1-1/4" Bore or even more.
Consider a 50 cal rifle is often built on a 7/8" oct barrel. A 54 cal...