miskied

Hi guys, I'm new to yotatech. Just looking for some advice. My 2.4L 2WD 97 has what I would describe as a mild to moderate oil leak coming from the vicinity of the timing chain cover and crank seal. I think it looks worse than it actually is because the leak is spilling/dripping onto a belt and it seems to be flinging oil all over the place (making pinpointing the exact leak difficult). Any how the truck has 190k on it. I have consulted the factory service manual and it looks like I will need to disassemble a good portion of the engine to access the cover and crank seal. I plan on installing a new water pump, new gaskets and seals for the crank shaft and timing cover, and a new valve cover gasket. Here is the big question: Should I also consider replacing the timing chain and guides at this point as well? Since so much of the engine will already be disassembled. From what I can tell Toyota has no specified interval for timing chain replacement and I was told by a mechanic that they only need to be replaced when the plastic chain guides wear out and the chain starts to rub? Is this true? Basically just wondering if I should go all the way now, or wait for the chain/guides to fail?

I plan on keeping this truck for at least another 100k, possibly indefinitely so I want to make sure its well maintained and cared for.

Any advice is much appreciated.

Thanks!