First, technically, whenever a commercial ammunition maker goes above the SAAMI pressure standards, he calls the load a +P+ load so as not to be using a SAAMI term like +P when SAAMI has no +P standard or when exceeding it if there is one. So I think you can legitimately use the +P+ term.
Second, whenever we discuss loads possibly outside the SAAMI pressure levels and not published by a reputable source of load data,
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Your objective in a sturdy gun like the Ruger, seems reasonable. The 32 H&R Magnum has only a copper crusher pressure standard, while the 327 Federal has only a transducer pressure standard, so you can't really compare them directly. However, the copper crusher numbers have the 32 H&R Magnum at 1.75 times higher maximum than 32 Long, and if you apply that ratio to the transducer number for 32 Long, which is 15,000 psi, you get 26,250 psi, so it is likely that if SAAMI produced a transducer standard for the magnum, it would land somewhere in that proximity.
I assume the LCR is already chambered in 327 Federal since I don't recall one having been made for the 32 H&R Magnum, but correct me if you know otherwise. The main thing is to have one with the steel rather than the aluminum frame because of gas cutting at higher pressures.
Rechambering the Blackhawk in 327 Federal, assuming the cylinder has the necessary length, would add flexibility. It would also allow you to use 327 Federal brass for your loads in both guns. Using reduced 327 Federal loads rather than +P+ 32 H&R Magnum loads avoids the possibility of the high pressure 32 H&R Magnum loads getting into a gun that isn't suitable for the pressures involved. However, collector's value of the Blackhawk may be lowered by rechambering. Also, if it is exceptionally accurate as it is, you risk upsetting that. These are the only two reasons that come to mind for not doing it.
If you want to avoid the 327 Federal level load because it is too warm and has too much blast, keep in mind 296/H110 cannot be safely loaded much below 90% loading density because of the danger of a round squibbing out and leaving a bullet stuck in the barrel for the next round to fire into. That is an event that usually bulges the barrel but can occasionally burst a gun, depending on where in the barrel the stuck bullet is sitting. So there is a limit to what you can reduce with that powder. Also, it is famous for muzzle blast and fireballs, so it probably embodies all you are trying to avoid. In your shoes, I would be looking at something like Hodgdon Longshot or Alliant 2400 which have loads listed for both 32 H&R Magnum and 327 Federal (H110/296 does not). That's a good clue they will function well at load levels in between the two.