I've read the recommendation here several times that when the factory starter dies (or even before then), that an easy/cheap/effective upgrade is to the later style L31 or LT1 starter.

I had the joy of taking a day off work today to change the starter on my L31 powered Express van. The starter has a hefty heat shield on it (good).



As you can see, the proximity of the exhaust manifold to the solenoid makes this shield pretty essential.

Are the clearances similar in an F-body? I can't imagine that they are not. Does the F-body use a similar shield? Or is there no room for one?

 

I've never used the shield, so I can't comment on the fitment but can say that without it, I've never had a starter issue. Heat soak related or otherwise.
I'm using Hedman LT headers and not manifolds though.
I should qualify that by saying that I did have alignment issues. It was necessary to use a shim to keep the starter gear from crushing the flywheel.

 

The heat soak issue with stock 3rd gens is usually only present after swapping in headers. I think the recommendations to swap in one of those starters regardless is largely due to simply being a smaller size. Personal experience: bought an 89 IROC with headers already on and a severe case of no start once warm, LT1 starter fixed.

 

I upgraded to an LT1 starter due to a no start after heat soak issue running SLP headers. It fixed the issue. I can now remove and install the starter without first removing the header now, and it weighs signifigantly less than the stock starter.

Other than it being a tighter reach for the wiring, I wouldn't hesitate to swap.