Two tapered pins, make sure to pound from the correct side, use a caliper to make sure which side is larger, then pound from the smaller side.
Make sure when you buy your new gas block you get the right size. There are a variety of gas block diameters, with 0.75 probably being the most common. Again you can use a caliper or micrometer to measure this.
Even if you choose to run only the electronic red dot sight, I would still recommend a fixed front and rear BUIS. You could consider flip up, but the rule of thumb is basically fixed sights with red dots and flip up sights with scopes. You can cowitness the sights or run the red dot a little higher. I'm told there is a mantra in the military that one is none and two is one. Basically meaning what will you do when the **** hits the fan and your primary sight goes down?
BTW your question is a little misleading because you don't have a scope, you have an electronic sight. To those reading this with MAGNIFIED SCOPES, the sight may not interfere with the scope at all because the focal plane of view is beyond the sight. The first time it was like magic, but I have shot AR's with scopes with the front sight present and the sight never appeared in the scope.