The extra bhp will translate more to top speed increase rather than in gear times if the torque doesn't increase much between the 300bhp and the 330bhp mods.
....Am I right in thinking that an increase in bhp but keeping the torque limited, will translate to more 'pull' at the higher speeds rather than an increase in the maximum top mph ?
No. Increasing BHP will increase v-max (top speed). Increasing torque (but keeping max bhp the same) will keep the same v-max, but allow you to reach v-max in a shorter period.
Torque is simply a turning "force", whereas bhp/hp/PS/kW are merely a measurement of power, or work. If you have a greater torque figure, then you are turning a shaft "harder", which means greater (better) acceleration.
