There are native speakers of Japanese who contribute regularly on this thread, so I will defer to them to fine-tune your words, if they choose to, but what you have now is polite and understandable, and not bad. It can be edited to sound more natural and more sophisticated, but what you have now is acceptable for something coming from a non-native speaker, I think.
The three things I noticed that should definitely be changed are:
1. There is a mistake with the second 申し. The correct Japanese here is もし, not もうし. It is most often written in hiragana, but you can also use kanji: 若し.
2. Instead of よければ, use the polite form よろしければ.
3. In this kind of request, it is essential to use the phrase よろしくお願いします. You can insert it in place of the 'thank you' at the end. You can make it even a little more formal and polite by writing どうぞよろしくお願いします, or even どうぞよろしくお願い致します.
Also, I think it is better to use your full name in the request. (Perhaps you were already planning to, but don't care to include it in the forum post.)
And you can use the Japanese word インタビューする for 'interview'.
Finally, to help entice the person you are inviting to agree to participate, I strongly suggest that you refer him/her to several already published news articles, so that he/she can see what they look like, before agreeing to your request. With a web link, or included as an attachment, etc.