Absolutely Acros or TMY2. The latter will be faster for any exposure shorter than a night even taking into account its slightly worse reciprocity. Both are far better than HP5 for this.

Your meter probably won't register at all. While some APUGgers will not like to hear it, a DSLR is about the best meter you can get in this situation: put it on high ISO with a large aperture and you can take very short test shots handheld (adjust exposure and repeat a couple times according to what you find on the histogram) then compute the actual exposure you want to use on the RB given the film's ISO and your chosen aperture. Think of the DSLR as a meter with a really large silicon sensor, some better-than-average optics and a nice histogram function that your average meter just doesn't provide.

Edit: don't believe Ilford's published reciprocity tables for HP5 or nearly anything else. The film has better reciprocity performance than that.