First I'd verify that you need more pump shot.
Do some testing and tuning. If throttle response is good, and transition to the secondaries is smooth, then no more pump shot is required.
A quick way to increase pump shot without trimming the pump shaft is to bend the arm coming up to the lever from the linkage. It can be straightened back out or replaced later. This will allow the pump to raise up some, and add more volume/delivery to the engine.
If testing shows the engine likes a bit more, trim the pump shaft accordingly.....Cliff