At this stage of the game, there's really no need to paper tune, unless you really want to. Your bareshaft flight indicates your close enough to just tune with your broad heads, and, based on the 75-80 flying a touch weak, that's the ones I'd choose.
Verify that they hit in the same spot as the same weight field points, and you're good to go.
For what it's worth, you mentioned the very reason I don't bare shaft tune wood arrows, broken shafts. I have a test kit made up of various spines that is perfect for finding the right spine. I just make sure my best educated guess for the right spine is pretty close. You don't want to be 20# off in spine weight. That can be really dangerous with a broad head and can also break shafts.
As far as shooting broad heads all year, well, no, not really. Once you're tuned, a broad head isn't going to fly any different than a field point or a blunt or a judo, unless it's windy, of course. Besides, broad heads tear up my targets.