With the extra width of the axle, I think full size 78/79 adj trac bar.
Also search out a Kiser Riser, a member on here makes them and they are ROCK SOLID BEASTLY. Nothing wrong with the WH riser at all, in fact I am using it on a 76 getting a 79 D44 right now. Built in progress.
Also research if you really need a trac bar drop bracket (off the frame) WITH the riser bracket on the axle. Some threads say NO. I am looking for the POC info on the "Kiser Riser" maker for you.