The turbochargers are the manual wastegate type, requiring you to monitor and adjust to prevent over-boosting. There are a couple ADs to look for on the RayJay turbochargers, fuel system, gear and corrosion. The IO-320 engine is reliable, popular and has good parts availability.
The aircraft is slippery and doesn't slow quickly. You will learn to plan your approaches to avoid having to cut power too rapidly.
In the olders models the panel layout isn't the familiar 'T'. The instruments are placed in a shotgun pattern. So you will have to modify your scan.
One thing keep in mind is many of the circuit breakers are under a small door on the floor forward of the instrument panel in the older models. The potential for vertigo is increased if IMC and you having to reach down under a floor panel to reset a breaker.
The airplane was fun to fly and easy on gas. Look for the PA-39 if you want counter-rotating props.