looking for the swap 67 to 68 tank straps thread

There aren't any brackets at front of straps req'd here. Some other model might have had some sort of bracket.
So on the 67 look at the upside down 'T' shaped opening they cut into the left frame rail. Maybe make a paper copy of it while there. Now go to the cross member ahead of the fuel tank and cut in two more of the same. Measurements to place these keyholes exactly where the factory did would be nice.
The straps placed and squared from the rear hangers will show you where they should go. A 1/2 inch off in any direction would hold the tank up.
If the one would hold for 67 , two share the load in 68. So there wasn't a reinforcement plate added to the cross member. Just two keyholes.