Here is the OldGMC site address:
http://oldgmctrucks.infopop.cc/6/ubb.x?a=cfrm&s=272004236When you go on that site, look in the "OldGMC Hall of Fame" forum.
I will be doing mine over again as soon as I move houses. When I rebuilt my 216, I put in a new seal. It worked perfectly for about the first fours hours of running and then all at once started to leak. I have been talking to a supplier about the types of seals available. He sort of hinted that the old asbestos type are better then what they make today but "Best Gasket" makes the best one that is made today.
I wasn't able to make the "Chinese finger" work on my seal to pull it in. I am going to use black fishing line this time around. Generally they don't give you a whole lot of extra length to play with so one has to be careful with the ends.