You have made a mistake with your retirement accounts that many people make. Unfortunately, the rollover of the 401(k) to a traditional IRA has caused your Roth conversion to be largely taxable because the taxable amount of your Roth conversion depends on the year-end balance in your traditional IRAs, not your balance in traditional IRAs immediately after the conversion.
Likely only a small amount of your basis in nondeductible traditional IRA contributions will be applied to your Roth conversion. The rest of your basis will apply bit by bit to each future distribution from your traditional IRAs until you have a zero balance in traditional IRAs at year-end.
