The factory 14" barrel with their brake is a good way to go. There are other aftermarket brakes which are slightly more efficient, but I'm not certain you'd actually feel the difference. With many loads this cartridge recoils fiercely, and I'd think hard as to your perceived "need" for this barrel. That said, it is manageable by many, myself included, and careful load selection can reduce the recoil a bit.
Accuracy can be very good if you can manage the recoil. It takes a firm grip and a consistent hand placement to get good groups. My 14" barrel got 5-shot groups in the 2-3" moa range with certain loads; ditto with my 16" barrel. Blast depends on the powder used - as does recoil to an extent - but the blast is far less to my ears than a 7-08 or .30-06. That makes sense since the muzzle pressure is far less with the .45-70.
I've hunted with the .45-70 for over 30 years and I've shot from deer up to brown bear with it. In a handgun it is only slightly less potent on the animals, regardless of the calculated energy. I like the 300-grain HPs for most game, although the 350 Hornady is tops for the large stuff. Recoil is less with the 300s, and killing power is ample. I like RL-7 and AA2015 powders for full power hunting loads, and IMR4227 for plinking and target shooting.