Try using the TaxCaster.
https://turbotax.intuit.com/tax-tools/calculators/taxcaster/
Your IRA withdrawals will be subject to regular income tax plus a 10% penalty if you are under age 59-1/2. Your cash buyout is probably a short or long term capital gain (depending if you held the shares more or less than one year).
Assuming it is a long term gain, and your total income is less than about $105,000, I think the long-term gain is tax-free. Otherwise, the gain will be taxed at 15%.
Without knowing your ages or the dollar amounts involved, your overall Federal tax could be anything from zero to 35% of the IRAs and 15% of the stocks. If you plug your numbers into the TaxCaster, you should get a close estimate.
Don't forget your state income tax. Most states tax capital gains as ordinary income and don't have a reduced rate. State tax rates can be between 3%-13%, depending on your income and which state you live in.
