Those sound really good, and good playing too!
What pot values do you have in your guitar and where's your pickup height at? Sometimes your amp may be close, or right and it's how you have your guitar set up that's taking something away from the sound. You definitely want 500k pots, around 550k if your using modern CTS pots. CTS pots can sound kind of muddy and peak in the high mids. Slash has DiMarzio rebranded Centralabs in the Derrig and Centralabs are much brighter with less mud and warmer highs than todays modern pots. The mids are slightly lower than how they sound with CTS pots. Just to give you an idea of how Centralabs compare to modern CTS pots, I have some Centralab pots that measured from 494k to 505k that I replaced some CTS made 'RS Guitarworks Superpots' with that measured 551k to 560k and the Centralab pot were much brighter and more open sounding than the CTS pots. Yet the highs were warmer, with a lot less mud in the sound. I quickly learned how much the Centralab pots play an important part in Slash's recorded sound, as well as the late 50's Bursts. Once you hear their sound, you will instantly recognize it.
As far as pickups go, according to Ace, Slash has both pickups in his Derrig set between 4/64" and 6/64". Possibly up to 7/64" with the neck. From looking at pics of the Derrig from back in the day, I'd say he hasn't changed them much. Raising your pickups will brighten up the tone somewhat. I'd start at 4/64" and tweak from there. APH1's are pickups you can have closer to the strings and not worry about them 'woofing' too much. Slash also sets the bridge pickup's screws to the radius of the fretboard with the low E screw setting flush and the high E screw 1/2 turn lower. Adjust the rest to the equal distance as the others, with the G screw setting the highest, maybe two full turns, and D close to it, but slightly lower by a half turn. The A and B screws are about the same height. Raising these will also increase the brightness of the pickup overall and give you pickup more balance.
For how he sets the neck screws, they are much lower, almost flush. He sets the high E the same as his bridge High E, and the low E, only about a quarter turn down from flush, with the D and B screws about the same, 1/2 turn up, and the G screw 1 full turn up. From pics I've looked at, it appears he rarely, if ever, changes how he sets his neck screw heights. They always look the same. Lowering the neck screws will increase the brightness of the pickup as it brings the screw coil closer to the slug coil, and equalizes the sound more evenly between them giving you a brighter neck pickup. Adjusting the screws like this gives you more balance verses having them flush. If you raise the neck screws too high, your pickup will get muddy as your bringing the lower sounding coil up in volume when doing this.
I'm sure you know this, but I just want to put it out there for others to think about if they're close. It always amazes me how much you can tweak your sound through the pickups alone.