Defo has to be a 150 but u also need to check it's stats as when it jumps to 225 something shit like food my get most of the boost, and Ur just breeding good eaters lol.
No only the 60 odd level u put on any Dino when tamed. It need to come out higher than 225 for it to be worth it. Otherwise I can tame a 150 I did get 239 pteras bit sure they can go higher if u 100 imprint and stuff on them and inbreed to get mutations of stats.
Basically get 2 150 and hopefully with good mele or what ever u need from it. They'll go to 225 and then u breed them and hopefully they'll come out higher than 225. If it's born 150 it means it's only like a LVl 110 tame.