thats sort of what a shift kit does. The TV cable adjustment will affect this somewhat. The other things that affect the 1-2 shift are the spring/spacer in the 1-2 accumulator, the setup of the servo, and the hole size that was drilled in the separator plate. The 1-2 shift is somewhat tunable, but you don't want to soften up the light throttle 1-2 at the expense of the full throttle shift crispness.
Most shift kits have some choices you can make relative to this. You need to check with your dad on these and see what he did.
Some of the other guys can help you tune it as well.
Bob