I've decided to install a wood insert for backup heat, have natural gas furnace. My masonry chimney hadn't been maintained prior to me buying the house and needs a few rows of bricks replaced along with a new crown at the cost of 12-1300. Problem is the weather has already turned and I'm worried about the concrete curing properly. Is there any reason I couldn't remove the 2 rows of bricks and then fab up and install a stainless chase cover and seal it? Would cut amd remove clay liner flush as I'll be installing a stainless liner and extending the liner with grade a 18-30"