Anyone using a professional products damper?

I used one, but for a 460. I think what you have to do is just bring it to tdc#1 and see where the timing marks line up. There were obviously several different timing covers made, so you just have to figure out which set of marks line up with your cover.
 
there were three different timing pointer locations, thus the three different sets of timing marks. pick the timing pointer location you want, and the timing marks should fall in place nicely.