If you don't like the "I don't like to actually see what I'm shooting at" AKA "I only shoot big things really close" AKA "Combat Sights" , change them.

That's the thing, I like shooting with the black sitting on the top of the front post not combat sight picture as SIG calls it.

My sights are 8 front and 8 rear. Would replacing the rear sight with a 10 move the POI up 2 or 3 inches

Sig Pseries sight heights move the poa 2" on the rear and 1" on the front. "numbers up, groups up".
Those displacements are in inches at 25 yds.
So the answer to your question is no if you mean at your 6 yd problem distance.
Round number math 6" low at 6y is about 24 inches low at 25 yds. There is no possible combination of available sig numbered sights that can overcome that. If you truly think its not you then you need to go to dawson and see if its possible to build what you need. A quick use of their sight height calculator shows not a chance. But this is their business and I would speak to them.