The heat gun should work fine. If you have a fairly large air compressor, you might want to think about sand blasting it yourself. Sets with the gun and safety equipment are available from large tool stores or by mail order. Then it would just take some bags of sand. A sandblaster is not hard to use. Dust control as far as you breathing it in is critical though. If you use the heat gun, you might still want to go over your stone to get the last traces of paint out of the cracks and crevises. Citristrip is a pretty safe product for this but you will still want to read and follow manufacturers directions. Henry