brinkman
Separate the two functions as they are indirectly related. Now, you already know how to modifiy the OEM bolt release so go for it. ....
On the modified rotary magazine, It is an after market product that has a little arm that hold the mag open after last round. For all the work I have done on these, I have never used one so not familiar with the interaction. I have only seen a picture of one. Most of the time, I can feel the last round or there after ....
Be Safe !!!