I'm sure most guys would enjoy helping out with a threesome 🙂
It really comes down to have some honest discussions about it. Let her know that just like her, it turns you on thinking about her taking on 2 cocks. Ask what reservations she has. If you each know the others desires, it'll be easier to make something happen. In the end, just keep talking about it and let it simmer in her thoughts. Best of luck.
And feel free to post lots of pics of her 😉