"You could go to a 2" less
"You could go to a 2" less pitch prop. This would give you more jump out of the hole.
Also something like a High Five prop allows the prop to spin easier from a dead stop so that the engine can get up into a higher RPM power band, and this really helps performance.
If you are not hitting at least 3000 RPM with a WOT dead stop almost immediately, you are turning too much prop.
If it's top end speed you want, you need more power, and the power required will be the square of the increase in speed.
I had a 4 bbl Webber on my 1996 4.3LX Vortec and it ran pretty well. What hp is yours rated at?
Rod"