340 has no timing tab...

yeah, it all interchanges. you'll need to remark your balancer for TDC. unless it already has one (some balancers do, or it could be an early or late one-- anything can change in 50 years).

remember though, the pulleys are specific to the early and late style, so you may have alignment issues if you have p/s or a/c but the alt. is usually pretty close and can be sorted with a little futzing about.

what side is the radiator outlet on? that may color your decision...
It's a different radiator than stock but it's on the passenger side period