I have a new client who for many years contributed after-tax $$ to his regular (NOT ROTH) 401k plan. 

He left his employer in 2012 and at the time had $100,000 in his regular 401k which consisted of $25,000 in after-tax contributions and $75,000 in regular contributions. 

When the 401k was rolled over bac in 2012, the pre-tax funds were rolled into a Traditional IRA and the $25,000 (after-tax money) was rolled into a separate Traditional IRA as well. 

Fast forward to 2020...the client's advisor wanted to do a Roth conversion, so the topic came up about how the client had contributed to a regular 401k with after-tax money, so he was wondering why he would have to pay tax on the Roth conversion. (My client had originally though that the after-tax money was rolled into a Roth IRA - which it wasn't).

So, the question is, can he do a Roth conversion now with the Traditional IRA that holds the after-tax money as well as the earnings on it for the last 8 years? Or is he basically screwed at this point because he should have acted within 60 days of the rollover back in 2012? Any help would be appreciated.