Just to let you all know, I had emailed Tim after checking out the article archives at this site and seeing the care and feeding article he'd done. One of the pictures from the article shows a side-air system on a Sheridan based marker, I liked how it looked and then looked up MAC-1 on the web. Low and behold they still exist and Tim still is interested in working on markers!!!
SO, what's the lesson here? We all have another valuable resource in Tim and his shop.