Gap filling on modified t97 ambi release

[870pumplover]

I finished the mod of a ambi release on my t97 using a standard Ar15 button. Heavy filing and fitting was required as well as drilling out and rethread of original mag release button.

Now there is a slight gap and I was wondering what the best thing to fill it would be ? Some kinda black epoxy? And suggestion would be appreciated.

Thanks

https://imgur.com/gallery/93uEA