Don't do it. You will not acomplish what you are thinking. The real value of proofing is to have a VERY knowledgable person inspect/measure as necessary the various parts of the gun before and after firing a VERY carefully controlled proof load. Simply firing a heavy load only proves that the gun didn't let go that time. You may do damage that you do not see.
I'd suggest you have the gun inspected by a knowledgable 'smith. If he says it is shootable, then feed it low pressure loads. 2 3/4" nitro loads of 7/8 oz shot at 5000 - 7000 psi and 1050 - 1200 fps are in most loading manuals and use easily obtained components. Remember, low pressure for the good of the metal and low recoil for the good of the wood. BP is not necessarily low pressure or low recoil. BP is for that flat boom, fire, smoke, and smell that nothing else produces.
BP is fun and certainly has a place in modern shooting. But, it is not the answer you seek for a assured safety.
Do NOT try to become a shade tree proof house. Please! For your own safety and the safety of a future owner.
