Gabapentinoids, which is a class of drug(s) including Gabapentin (Neurontin), Pregabalin (Lyrica) and Phenibut among others, do have a not-so-well-known propensity to produce convulsions in high dosages. The issue here is that I don't know if the convulsions produced by Gabapentinoids are of the same pathology of epileptiform-convulsions. Basically, there are multiple issues that can cause you to convulse and they are not necessarily of the same cause in all cases.
As far as I'm aware, Gabapentinoids are not known to cause epileptic seizures, whereas Bupropion (Wellbutrin) does seem to produce convulsions of the typical, epileptiform-type.
Your best bet is to approach the situation with caution, as we all must do. Don't start by taking insane amounts of Gabapentin with your Bupropion. Dip your toes in the water and see what happens. I know this isn't the most fun or exciting way of approaching drug usage, but it'sthe best way to minimize serious issues.
If you want my absolutely personal opinion, Gabapentinoid convulsions don't seem to be epileptic in nature. I've had seizures from different drugs before. I've had my limbs flail around as a result of Gabapentinoids, though I've never experienced a true seizure from these drugs, so my opinion is that these side effects have a different pathology.