350 turbo trans

[LS short box]

A car buddy of mine has a 350 sbc and 350 turbo combo in a Camaro.
He's trying to get the trans to shift at a higher rpm under medium or a little over medium throttle. Are shift points controlled by vacuum or govenor?
He was talking about adding a stall converter but I don't think that will affect his shift points or will it?

[AussieinNC]

If the trans has an adjustable modulator you can perform the following....

Remove the vacuum line from the vacuum modulator.
Use a small slotted screwdriver to turn the adjuster that is located inside of the vacuum fitting.
Turn the adjuster clockwise for earlier shifts and counterclockwise for later shifts.
Make small adjustments of 1/8 to 1/4 turn at a time.

If the modulator on the trans now is not adjustable, I would replace it with an adjustable unit. If there is no
small flat drive screw inside the vacuum port pipe on the modulator, it is not adjustable.

At least half a dozen shift kits are on the market for the TH350 transmission.
They all share similar components and are designed to improve shift performance by increasing line pressure,
volume of fluid to the clutch packs, and timing of the shifts for less overlap and shorter/ firmer shifts.