Gen II heater core

coolant, firewall, template, core, tubes, hole, outline, pulled, heater, replaced, grinding, trace, plan, coming, undecided, metal, sheet, back, piece, wheel, making, time, miles, 110k, years, paper, forms, located, cutting, replacement

I have pulled the heater core and replaced it according to the BGB 7 years and 110K miles ago. Its time to do it again. Has anyone ever pulled it out and replaced it by cutting a hole in the firewall? I have a replacement core. I am making up a paper template that forms the outline and located via the coolant tubes. I plan to put the template over the coolant tubes and trace the template outline on the firewall. Then cut the firewall with a grinding wheel. It will all go back