Jonathan, nice buck for sure! I hear ya on the "whew" once he was found! (grin)
Things to consider are definitely arrow wt for head being used, more importantly is head wt & sharpness of broadhead this is where the ultimate penetration is stemming from!
I shoot a longbow at 55# 27" draw like you do, tuning is important but not an end all so don't pull your hair out if you get a slight flip on release out of your arrow, you need reasonably good flight. I get a flip every time I shoot but it corrects itself after a few yards or so within reason.
In your case putting a big Snuffer through a deer in the angle you mentioned would be very tough to do unless you hit a clear path all the way through, that head is big & can be restricted much easier than a smaller head.
If I were shooting that big head I would opt for more arrow wt closer to the 580-600grn mark, more importantly I would want 200grns min up front & razor sharp, this is where more penetration can be had. Don't be too concerned with pass-throughs, if you get one great, but it's not needed in most cases with a razored head carving things up while still in the animal.
Now if I chose a smaller head such as the SnufferSS in 3-blade or a 2-blade with bleeders I then would opt for an arrow wt of no less than 500grns but still have the 200grn wt up front. This is what I've been shooting the last couple of years. (thanks OL)
Keep one thing in mind when building an arrow. What are you hunting & what are you using for a head? Build your arrow accordingly, too, you will receive no penetration difference until you have aprox a 75-100grn difference in jump if you just add the wt throughout the arrow, but add that wt to the head area & now you've accomplished something! This is where the tuning comes in to get the right spine arrow for the desired head wt.
As an example I've shot the SnufferSS in 125 grn with a 75grn grn brass insert for 200grn head wt with an mfx beman yet my total arrow wt is 500grns I've taken 2 animals with this setup, one a 6-point bull elk at 18yds & the 2nd a mule deer buck in the 250-270# range at 32yds both were pass throughs. I took a 2nd 6-point bull with the same arrow wt of aprox 500grn with the same SnufferSS head on a 2018 aluminum. That arrow buried to the feathers as it stuck hard into the off shoulder, he was quartering to me.
My point is I'm getting plenty of penetration with this setup. If I were to use a big ole Snuffer head I would have to up that arrow wt a 100grns to push that big head in. 50grns more would not be enough, as your results would be minimal in the testing I've done! Good Luck!
ElkNut1