273 318 interchangeable parts

But,I don't want to have to change the ps pump,rad. Cant you just swap the 273 timing cover,balancer,pumps & etc over to the 87 318?

Yes, I just thought it would be easier to just change the radiator. That is what we did in my brothers 67 Barracuda. You will also probably have to drill and tap the smog holes below the exhaust ports. Make sure the set screws are below flush with the port face. When you change timing covers and balancer, leave them at TDC that way you can check timing marks. I've seen them way off.