A look at the photo shows that there is a possible clearance problem between the fuel pump arm and the double roller chain due to the additional width of the chain.
If performance is your objective, you will have installed a double roller timing chain. There are a couple of timing related items to fix in our big Buick timing cover. First we will take care of cam walk by building an adjustable cam button that will keep our cam where we want it.
Run down to the hardware and get yourself a 1/4" brass screw and some JB weld. Take the top off it as shown in the cam button picture. Drill and tap the original cam stop on the timing cover. Screw your cam button into the cover and observe how far into the water pump cavity it projects. Take it out, and cut it off so that it doesn't stick into the water pump cavity. Cut a slot into the water pump cavity end of the brass screw so that when you mount the cover, you can adjust the screw.
Mount the cover and make sure the screw is not already in contact with the cam. If it is, you will have to grind off a bit of the original cover button so that you can withdraw the screw to give you clearance on the cam.
Now mount the timing cover with the gasket. You should be able to feel that the screw can move in and out between the cam and the cover. Screw it in until it touches the cam, then unscrew it about .005" to .010". One full turn on a 1/4 coarse 20 tpi screw will be .050".
Mark the 0 point on the water pump housing for future reference. Remove the water pump. Remove the screw and put some thread sealant on it, reinstall the screw
Mix some JB weld and place it under the head of the screw. Back the screw out to the 0 reference point. Now back it out the estimated amount and let things set up.