what size pump

At the present time I have a 3/4 hp submersable (fairbanks morse) pump, the well is 40 feet deep, age is approx. 24 years old. I would like to upgrade the system (pump and pressure tank) before I have a failure due to age. The old pump records state it tested out at 40 gpm at time of installation. Two years ago I installed an underground sprinkler system, the pump will run three sprinkler heads putting out around 12 gpm at 28 psi continously. With the new upgrade I would like to get up to 20 to 25 gpm with a higher pressure, possibly 50 psi continously. The local pump man says not to go for the higher gpms as the well could possibly not handle it. I would entertain any advise on this situation.
Thanks
Bob

I think you meant your well tested at 40 gpm not your 3/4hp pump.

I would listen to your Well Man. He would be the best one to give out that kind of info.

bob...