Welcome to FTE.

This engine has flat tappets with hydraulic lifters.

Something like Shell Rotella 15w-40 would work methinks.

That zinc thing is mostly for break in afaik, but it isn't a bad idea to watch that with an older engine.

Shell Rotella® Products | Shell Rotella

As far as your prep, sounds good. Not sure I'd change the alternator.

5 mpg is what I'd expect.