Everything I've read has suggested that for my twist rate, a flat base is far easier to produce reliably consistent results whereas the boattail is more sensitive to factors not being perfect and there's the issue of propellant gas blowby on boattail projectiles which CAN?MAY cause instability as the bullet exits the muzzle and the cloud of gas, the following is a link to one of my references
https://www.gunsandammo.com/editoria.../375628#replay
The second number you dismissed is energy at POI and my understanding is that the rule of thumb is 1000ft/lb is reckoned to be the safe minimum on medium size game or am I missing something?