Most Boilers of this vintage were probably patched with some sort of cement containing asbestos at one time. Just like lead paint. Using the same logic, iven the age of the boiler are u concerned at all with the presense of lead paint in the house? If the boiler has been regularly service by a competent technician. Most of the Asbestos laden material has probably been removed and/or sealed over by paint. If any concerns persist have the air in the house tested. Since it's being torn out reccommend having it removed by a certified Asbestos mitigation firm.