whats wrong with off the shelf converter?

OK guys,
you talked me into getting a new converter with a new trans.

But...do I need to shell out $350 on a custom converter?

My car is and will always will be, well, a pu$$y ride, beach cruiser, heavy stock vert. Just looking for crisper shifts, manual shifting, and a modest improvement over stock.

Can I just stick in a B&M torque master from summit for $156.95 or a bone stock Ford replacement converter for $200. How about a Mark VII converter?

Also, what are the DOWNSIDES to a slightly higher (like the 2000 rpm) converter than stock? How will it feel different?

Thanks!