Code G is never to be used for a Roth conversion from a traditional IRA. Code 7 by itself is the correct code. After entering the form details, indicate that you moved the money to another retirement account, that you did a combination of rolling over, converting and cashing out, then enter the amount converted to Roth. TurboTax will include the taxable amount on Form 1040 line 4b.
Note that if you have basis in nondeductible traditional IRA contributions, the taxable amount is calculated on Form 8606 Parts I and II.
