My own preferences fall pretty far on the Dialogue side of the spectrum, so what I would do there is break up the narrative with some of the character's direct thoughts--essentially he's talking to himself.

On the other hand, I personally favor narrative. I think the idea you described could work really well to build up suspense--or, if you drag it on too long, you could frustrate and turn off your readers. You'll probably need to just play it by ear, and let someone else look over it. How much narrative you can pack in depends on your style of writing and what audience you're trying to reach. I don't think there's a set-in-stone limit to it.

First rule of thumb... if it bothers you, it MUST be changed. Otherwise, your reluctance and unsureness will show through in the writing and others will be bothered by it too.

Despite my criticism (which I meant)... I honestly think you show a LOT of potential as a writer. Maybe try that rewrite you hinted at and then share the new version with us. I'd try to get to some dialog sooner. Or at least experiment with other exposition methods.

Get to work and show us what you're capable of. I look forward to seeing more and helping where I can.