I must say that in all the bands I played in through all the years I was gigging, this song was never on the set list....thankfully. We had our share of nauseating songs that everyone wanted to hear, over and over to make up for it though. Swinging, wipeout, freebird, .....
My first thought was that is was hollow. In this song, you have a very stark contrast between the fat almost too heavy bass and the bright, almost brittle sounding guitar. As Frank said there seemed to be a hole in the middle of the music.
I played for several years in a 3 piece band and it was at times a real challenge to keep the music sounding full. Quite often we were playing the same clubs and circuit with bands that were at least 4 pieces and at times 6 pieces with keys and steel. As a result, I was kind of forced to learn to play using chords and two note things. The bass player also learned to play some 2 note things in places where I was soloing. The solo that starts around 1:20 starts one note.... then you grab some 2 note stuff.... that fills it a bit.
I have seen ZZ Top live a few times and they are the quintessential 3 piece band.... they had tracks or someone off the stage throwing in the rhythm. They do it all the time on their studio stuff and it's there in the live venue's too.
Changing the tone a bit on the guitar to mellow it a bit.... and unless it is a strict "we only record what we can play live" policy, don't be afraid to use another middle timbered instrument to fill the hole. The bright guitar would work better with something else in the center. A nice B3 floating there in the background, not too loud would fill the hole nicely and keep it in line with the sound of the era.
On the plus side, the cover was good, well done. Some creative picking in there that I really liked. The progression of the song lends well to playing nice harmony voicing, with that country feel.