That is where I would shoot. the "boiler room". (heart, lungs, liver). I have shot a lot of deer & that is where I aim & take them. Both firearm & arrow. If you are confident in your shooting ability & your firearm, then of course you could go for a head or neck(CNS) shot also. But the target area is much smaller & thus changes your odds a bit IMO.
BTW, speaking of using an arrow. They do not expand either. Their twisting motion with a broadhead does most of the work. Cutting rather than "punching". They are traveling slower than your loads by about roughly 2/3rds. Your boolit will be causing at least as much damage if you hit the boiler room. If you hit a rib or part of the shoulder, your bullet should either flatten or fragment, depending on your alloy used. Either way, if it hits any bone, they cause damage also.
I think you are getting over concerned, but of course, that is "my" opinion.
Go out & have fun! I think you will do just fine with either pistol. People around here hunt with 44 Rem mag and 240gr. bullets quite a bit & have no issue dropping whitetails. ( I have myself) Your pistols with a 310 should have no trouble either in 45 Colt.
You can go look up the projectile weight, the velocity & distance & use a formula( I think there is one here at CB, but you can google to get the formula) to figure out what momentum force is applied for your setup at impact(Ft/lbs IIRC) & compare it to other setups also. I have heard some folks say that any projectile that travels 100 yds & still goes thru a piece of 3 ply plywood will have the force to kill a man. I reckon that would be the same for a deer, although they are some tough animals. I have no doubt your setup will be just fine for them. Here is just one calculator to try. I punched in your data & it was equal to a 44Rem Mag. w/240gr, , BTW.
http://www.handloads.com/calc/quick.asp
G'luck! Bring home some meat for the meat pole.
[P.S. - I go out with my oldest in a week for our deer opener. We are in a Shotgun zone. We can use pistols over .357 or muzzle loaders also, but we are still just going to use shotguns. Using the slug shells I reloaded with Lee 1oz slugs I cast also..
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