Now that you have the initial cut, you will need to get to cutting some bone. You will want to remove all the internal organs in one smooth step. This will include, heart and lungs, as well as all digestive organs. You will need to cut through one side of the rib cage so you can get at the heart and lungs, and the middle of the pelvis so you can remove the intestines. My knife cuts ribs just fine but doesn't do as well on the thicker pelvis. You can use the electric saw for that, but I wouldn't. Too much risk of tearing intestines. I used a hack-saw for this animal because it gave me the control I needed to keep the blade well clear of the innards.
There is a thin membrane that attaches all of the organs to the inside of the body cavity. You will need to begin at the bottom by lifting the anus through the gap you created in the pelvis. Lay the five-gallon bucked down next to the carcass and place the intestines into it. Continue separating the organs from the body cavity and feeding them into the bucket as you go. They should just about fill the bucket when they are all in there.
Spread the ribs and cut out the heart and lungs. You don't need to be too concerned about punctures at this end of the carcass because getting blood on the meat won't affect its quality at all.
If you like haggis or want to make your own sausage, you may want to keep heart, liver, lungs, stomach, or intestines. That's your call. If you don't know what a haggis is, check this
out. Personally, when it comes to organ meat, I'm out.