The other answers have suggested some ideas on how to simplify the part, so I'm not going to go into that. Instead I'll try to offer an approach towards playing the part as written.
Having pulled up the trusty SG, which should be somewhat similar to a 335 in terms of playability, two things immediately become apparent:
There doesn't appear to be any smarter way to finger this than (low to high) 3-1 on the F minor third interval and 2-1-3-3-4 on the Db13,
%X.X.X.XX.6/3.4/1 %X.4/2.3/1.4/3.4/3.6/4[Db13]
There are two fundamental difficulties here: the two-fret shift to the chord and the pinky stretch needed to grab the 13.
Now that we know where the trouble spots are, we can proceed to work on them.
The first thing I suggest is to move the whole section to a higher position - VIII seems like a good place, being neither too far spaced, nor too crowded. Focus on just the one change that's causing you trouble and check the following:
Can you play the change from the minor third interval to a dominant 9 chord without too much difficulty?
%X.X.X.XX.10/3.8/1 %X.8/2.7/1.8/3.8/3.8/3[F9]
How much trouble do you have with going from the interval to just the top three strings of the dominant 13?
%X.X.X.XX.10/3.8/1 %X.X.X.8/3.8/3.10/4
You'll need a clean fingering of the dominant 9 for the last note of the bar, plus the majority of your final dominant 13 will be drawn from this shape, so it's a good idea to get this less tricky change down first.
The pinky stretch with a 3rd finger half-bar is the other tricky move here, so it's worth isolating this particular bit and making sure that it is confidently executed. If you have problems with this simplified fingering, you'll need to practice this change a bit.
So how would I go about crafting a couple of exercises to work on this particular change? Here's a general outline:
Step 1 : Alternate between one and the other, but mix it up in terms of rhythm. You might start with something simple like whole notes, halves or quarters, but you'll want to get a bit more creative as you get better - possibly throwing in some shuffle or swing rhythms in there. Try writing out a couple of bars of rhythm slashes and just playing the change over these rhythms (change every note), ideally with a metronome.
Step 2: Start small: treble strings only. This allows you to focus on getting the half-barre and pinky stretch down. Once you feel more confident, add the 1st finger 3rd on the D string. Finally, add the 5th string root to complete the chord.
$2.10.$1.8 $3.8.$2.8.$1.10 | $2.10.$1.8 $4.7.$3.8.$2.8.$1.10 | $2.10.$1.8 $5.8.$4.7.$3.8.$2.8.$1.10 |
Step 3: Work on changing to both the dominant 13 and the dominant 9 chords. You might also want to add the final 13-12 movement when doing the exercises outlined in step 1.
$2.10.$1.8 $3.8.$2.8.$1.8 | $2.10.$1.8 $4.7.$3.8.$2.8.$1.8 | $2.10.$1.8 $5.8.$4.7.$3.8.$2.8.$1.8 | $2.10.$1.8 $3.8.$2.8.$1.10 | $2.10.$1.8 $4.7.$3.8.$2.8.$1.10 | $2.10.$1.8 $5.8.$4.7.$3.8.$2.8.$1.10 |
Step 4: Once you feel pretty confident with the full change in VIII position, it's time to take it down a step to VII position. Repeat the exercises outlined in the previous steps until you're satisfied with your results and move it down a step again. With each position change you'll need to get a bigger stretch of the pinky, but if you've been dilligent in practicing in the higher positions, you'll have a much easier time, because you'll have only one finger to worry about, instead of four.
Working along these lines you should soon be able to play the change in the target position. However, it might also be a good idea to practice it a bit in lower or higher positions anyway. If nothing else, you will get changing to this dominant 13 shape rock solid.