Good question. I am going to replace the 302 (not original) in my 67 XR7 with a 351W and I am going to add performance parts. I have obtained quotes from three performance shops in town. One of the three has quoted me the edelbrock aluminum heads and the other two shops have both quoted the TFS twisted wedge heads for use with the 351W. Obviously two of the three performance shops believe the TFS on a 351W are better than the edelbrock. However, I know from speaking with these guys that if they were dealing with a 302 they would all quote edelbrock. Any direct experience out there with a 351W and edelbrock vs. TFS for heads on a 351W?
The Edelbrocks are probably better if you are installing them on an engine without replacing pistons. This is because the valves are in the stock locations and for the most part the valves will not hit the pistons unless you go hog wild with lift and duration. If you do then valve reliefs will have to be cut deeper into the pistons.
The TFS "Twisted Wedge" gets its name because the valves are slightly relocated. This causes clearance problems and bent valves will result unless Trick Flow spec pistons are used or properly located valve reliefs are cut in standard pistons.
The Trick Flow heads are supposed to be better, all other things being considered but will be slightly more complex due to the piston / valve clearance issue.