Equalizing My Arms

Hey there,
I've been doing PMO for about 7 years now pretty damn regularly, and I'm just starting to go clean now. As many of you probably know, after 7 years of M on a regular basis with one arm, the difference between my two arms is ridiculous. My right arm is muscular and veiny (especially the forearm, it's ridiculous), meanwhile I genuinely can hardly see a difference when I flex with my left arm. Now that I'm quitting, I'm hoping to slowly (I know it'll take years) get my left arm to look like my right arm. First of all, I know it will take years in all likelihood, but I'm okay with that. My problem is that I'm unsure which of the following options would get me there faster:
1) Do some light workouts on both arms and my entire body, but just constantly do really intense stuff on my left arm. Just exclusively give it the workout M exclusively gave my right arm for 7 years. This seems like it'd equalize them faster.
2) Work both arms out evenly. Whenever I talk to a doctor about catching my left arm up to my right (it also has a disability I've been working on with doctors), they say I should just work out my left arm as much as I'll work out my right. I don't know why this is better, it just seems like it'd take me longer to catch my left up because my right would still be growing.
Anyone who's dealt with this before, what do you recommend? For reference, I was thinking of buying one of those Shaker Weights and just doing it on my left arm for 10-20 minutes every day.