I am not sure about converting to extract, but I have a Belgian IPA in bottles right now that is pretty fantastic. In place of the Pilsner malt you could probably just use Extra Light DME to get the right amount of fermentables:
Batch Size: 6 gallons
90 minute boil
OG: 1.064
FG: 1.006
ABV: 7.5%
IBU: 54
Yeast: Wyeast 3787
12.5 lbs. Belgian Pilsner Malt
1 lb. Caravienne
.5 lb. munich
Hops:
First Wort Hop: .5 oz. cascade
60 minute addition: .5 oz. centennial
20 minute addition: .5 oz. summit
15 minute addition: 1 oz. centennial
1 oz. cascade
.5 oz. amarillo
Flameout addition: .5 oz. summit
.5 oz. amarillo
Dry Hop: 1 oz. amarillo/ 1 oz. centennial/ 1 oz. summit
If you are using extract, you might want to sub out some of the gravity points from the DME for plain table sugar to dry your beer out, as I imagine hitting 1.006 will be pretty difficult. At only 54 IBUs, the dry finish is necessary to get that firm bitterness people are looking for in an IPA. I also think the 50-65 IBU range is perfect to allow just the right amount of yeast character to shine through. The hop profile is very citrusy, and the aroma punches you in the face without being harsh or overly bitter. Very drinkable.
I spent a lot of time looking for Belgian IPA recipes myself, and there aren't many out there. You will probably just have to pull from other recipes until you have something you feel confident with and can improve upon the next time.
Good Luck!
