Starter heat soak

Hi at all,

I read a lot to the topic but i just cant get it working.

To my setup:
Its a 1974 Plymouth Scamp with a LA 408 stroker and full length Hooker headers.
The headers are wrapped under the starter and the tube which goes over the steering is wrapped in the starter area.
First i had a no name mini starter (which worked with my old headers who were fully wrapped) but heat soaking after a short drive.

Then I bought another mini starter from rockauto also really cheap still heat soaking.
Tried a starter heat wrap + a selfmade aluminium heat shield which covers the left side and the underneath of the starter.
Still not working when the car was running for a while.

Now i just got a powermaster 9300 starter, wrapped it in tin foil (read that somewhere here in the forum) + the starter wrap + the selfmade aluminium heat shield. Still not working when hot.

Cables are all new, + directly from the battery in the trunk to the starter with a massive cable, starter relay new, optima yellow top battery with over 12.5V,
timing was an 12 initial but now i put it to about 17 initial and the headers are a lot cooler after this, but still the starter turns only really slow or barely when the car is hot and it wont start up.

I dont want the wrap the headers full,
any other suggestions??

Thank you all,
Laurin