Yes I have aftermarket 1 1/2"-12 threads on my housing. The charts are wrong, its like banging your head against a wall. The Donaldson I found was for a Big Cummings engine but looked like it would work. I can get that with my Amsoil Account.

Ive seen some Baldwin filters go down to 9.8 micron...
Just wondering why you want to go so small?

Go with what your builder said

Everyone has opinions, mine is, I like better filtration but with a high volume oil pump its moving a lot of oil. Reducing the particle size may reduce flow (don't know). Going smaller may need to use 2 filters in parallel to keep the flow up

20 micron seems to be the standard, Wix racing is 60 micron.

After doing a bunch of research the Fram HP6A seems to be the best filter for the bigger 1.5"-12 filter threads. 20 micron rating, 20 psi relief valve with a screen, thicker metal. The standard filter by Fram is low quality cardboard, however this one seems to be built he best.

I use the Donaldson P550832 from Amsoil. It has the flow of the racing filters and super fine filtration, the best of both worlds.

That has the standard chevy thread size, no ?
https://shop.donaldson.com/store/en-.../P550832/20534
OP has something totally different.

I used to use that one, I now have a 1.5"-12 stud. Completely different filter. Been looking for a cross reference to Donaldson or Amsoil with no luck. The Fram HP6a seems to be the best.

Yep, wrong stud size. I still have one sitting on the shelf.

Saw another post on FB that compared micron rating, flow rate and pressure from an episode of Engine Masters where they tested a bunch of them. I used to run the Wix Racing 51222R and switched to the K&N HP-5001.