The biggest issue is flare potential. If you are talking about a low flare ball, then the difference between a 5x3 versus a 4x2 isn't as great as it would be with a high flaring ball.
A good ball to think about is the old double-puck Ebonite Stinger. That ball had a very high RG and would go very long with a 5" pin. But it also had a big differential and a stronger drilling (in powerful hands) would create so much flare that it would kill the length. (This example comes from a personal bad experience]
With that said, I think on a medium flare ball, you are on the right track. I'm sure you'll have to combine the drill change with surface tweaks, but you can get there.
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Good luck & good bowling