Rebuild or Not?

[fordshy]

I am having the timing chains replace in 97 ford explorer. Now that the engine is dropped and apart, the mechanic says that the inside is worn and needs a rebuild. He says that is will last another year or so before it starts burning oil etc. Except for the rattling timing chains it was running fine. Not currently using oil and exhaust does not smoke. It is running smoothly and has good power. Should I rebuilt or wait?

Thanks