I 'entertained' the idea of having only one flintlock to do it all and settled on a 16 ga. smoothrifle. The idea originated around a longrifle amply capable of taking both deer and turkey in GA, where I resided at the time. After lucking into a very early Getz 16 ga. (.652) barrel and purchasing a lock from Jim Chambers, Allen Martin built that longrifle, for me, inspired principally by Newcomer and Fondersmith (and other Lancaster elements) it was featured in the Contemporary Blog, about 07, December 2012.
If I wanted another 'one to do it all' longrifle, I'd stick with that same decision.
Good luck!