You need a big drill
Your choice really.
A
TCT (Tungsten Carbide Tip) drill is fairly cheap and can be used in a hammer drill with enough oomph to drive it. Biggest downside is that you tend to blow the back out just as you can do with a regular impact drill - ie you get so far through and then the back of the block flies off. If it's soft internal block then you can cut half way through the outside block from the inside and probably avoid that. The (smaller) ones I bought from this place also aren't that deep - so they won't go through a 4" block in one go.
And of course, just like regular impact drilling, it makes a lot of noise.
A
diamond core drill probably does a neater job - you aren't using impact to cut. This is important, you do
NOT use these as impact drills, you use them without impact and the diamonds do all the cutting (thousands of tiny diamonds, each taking tiny cuts). They must be kept well cooled/lubricated with water or you will burn off the diamonds very quickly.
In terms of what to drive it with, for infrequent DIY use you can get some SDS drills quite cheaply these days - such as
some of these. The Duratool stuff is "OK" for light DIY use, but just don't go fooling yourself that it's going to be equal to the better Pro stuff. Get some chisels and they are quite useful for chasing out for sockets and stuff as well.
But it all comes down to how much space you have to store stuff, and how much you are likely to use it. If you won't have any further use, then willsgas has the right advice - get someone to do it while they are in the area and it won't cost you much. Just have the position marked and power ready, they'll be able to make that hole for you in a few minutes.