Originally Posted by Celestial Mechanic

Wrong. There is only one constant in standard Einsteinian General Relativity and that is 8*pi*G/c⁴, chosen in order to have Newtonian gravity as the weak field/small velocity limit. Any good GR textbook could have told you this. It does not bode (or even Titius-Bode!) well for your conjectures that you have something as simple as this wrong.

As for the alleged "failure" of GR in the other planet's perihelion precessions, I'm looking for the current best estimates, but the fact remains that because of the smaller effects and smaller eccentricities it is very difficult (especially with Venus) to verify this. But I'm sure it has been done. Hint: Do not cite the "works" of Santagata in this context; they are absolute rubbish.