Welcome aboard eman9502.
The FB model was only produced up through '71. We have seen boats sold in '71 but not registered until '72 but certainly not '74.
We have a member that put a 250 on his flatback and he said that it was too scary to drive anywhere near wide open. The FB was originally designed for a 90 hp and most people are more than happy with a 150hp on it.
Be advised that a FB has a tendency to "bow steer" meaning that if a wave hits at the wrong angle the bow could dig in and all of a sudden you're pointing 90 degrees from where you just were. Pretty dangerous.
If you have a 12 degree hull, which was made in '74, you would be pushing the edge with the 250. most have a 200 or 225. The original specs were for a 140
