As someone who laid out a game in typewriter font, here's my 2c.
First of all, let's look at your non-typewriter options.
Serif fonts (unless inspired by the programming fonts with its geometric forms, monoline weights and slab like serifs) will create a wrong feel to the text. It will either push the text more towards fantasy (not sci-fi) literature or everyday mundanity. I don't think it is something you would want.
Helvetica is the vanilla of the font world. It is perfectly fine, and will seldom clash with other flavors, but it will not add that much on its own. If you are going for no-nonsense, direct approach (or you are at a deadline and need something to just fit in) - go for it, but you can't really "season" the text with Helvetica and give it a theme.
You can season with Avenir. The futurist roots of the font, mixed with a bit of playfulness fit the theme of Agents of the O.D.D well. Not to mention, manuals for big organizations would often use sans serif fonts, as they were the non-nonsense new hotness when manuals became more of a thing (1960s). Sure - this is the time that Helvetica rose to power, but it became so ubiquitous that it lost its flavor. If you decide to go with non-typewriter typeface, Avenir is a good call.
...and now for typewriters.
The font you currently have is very distressed. It looks like it was made on a beaten up typewriter, with over-saturated ink ribbon or pulpy paper. It gives it a LOT of personality and creates a time and space around it. I love it... but yeah, it is not great for body text.
The big issue here is the texture. The jagged lines look cool, but they also "vibrate" on white page (especially on the screen) and make our eyes tired. You can experiment with minimizing it by mimicking how it would look made with actual typewriter or actual paper. After all, people are perfectly capable of reading (even beaten up) typewritten text without much issue. The problem here is contrast.
Unlike fonts, typewritten text like this would have a range of values. The ink bleed (what gives those letters this jagginess) would be lighter than the core of the letter and it would flow better with the page (which would not be pure white, nor would it shine light into our eyes like screen white does). The font has a very noisy change between the white and black - this jagged change makes our eyes tired. You can try to minimize this eye strain it by not using a pure black for your text (maybe something around #1a1a1a instead) and not making the page pure white. Give it a bit of yellow or just grey it our a bit. Even if you have the #1a1a1a text and an ecru page it will still read as pure black & white - but it will be much easier on the eyes.
Another idea is to create more whitespace on the page. Leave out some spots for the reader's eye to rest safely away from the noise of the font.
Of course - you can try using a different typewriter font. One that is not a crisp and perfect recreation, but also not as distressed. This is what I ended up doing for Endure. I used F25 Executive - it still has a bit of ink bleed (giving it almost a humanist like aesthetic), but it is not distressed to the point of being noisy. For me it was a good balance between machined and man-made look.
...and for keeping it looking like an artifact from the time & place - you can still keep the headers in a sans serif font and make it look like it was made few decades ago using office supplies. After all Letraset was a thing, and many offices used it :D
[it ended up being much more than 2c, but hopefully it was worth to spend the time reading this]