Some are more prone to akathisia than others. I do know that withdrawal induced akathisia sucks. Benzos help but are extremely addictive and cause a dependence far worse than buprenorphine and worsen depression.
Ropinirole or pramipexole could help maybe. Or extracts from mucuna pruriens readily available online (containing l-dopa) might help but this is just a guess. Might help.
A big part is the rate of decrease. If you are having a hard time decrease slower. You could even grind up the pills into a powder and put it into solution and decrease in tiny amounts. Every day down is a day down however incremental.
I got off of 380mg of methadone years ago, took me a bit over a year.