Outer Sill Replacement - all or just the ends?

I am in the process of replacing the outer sill on a 74 GT. It appears the only rusted out parts are the 2 ends. I have a heritage replacement sill and was considering just cutting off repair portions to fit the rusted out parts. Before I started cutting the new sill I stopped and was pondering if I should just do the whole sill. Then I started counting the spot welds and I'm back to just doing repair panels. Here are 2 pictures of the sill front and rear. I can see in the outer sill from front to back and other than some spider egg cases and dust there is no rust to speak of.
Any advice?

Normally I wouldn't entertain the idea of partial replacement and with UK cars it's rarely an option but those sills look remarkably good, that exposed rear particularly, and I can scarcely believe that what I'm seeing is an unrestored 74, so in this case go for it I say.

The less metal you have to replace, the better. No sense doing a complete sill replacement by the looks of your car.

Here is a picture of the inside of the sill.

As long as you are comfortable with the welding, just do a patch job. The outer sill is more decorative than stress member.

thats how they did mine

Rick,
It looks like the sill area need to be treated before closing up?

This car has 57K miles on it. I just bought it along with a parts car of the same year. I also have a 74 Roadster with about the same number of miles and the body on that is original other than the passenger side rear dogleg is just starting to bubble up rust below the paint. That one I have owned since 1978.