I have Marlin arms and dont think it would weaken them by tigging some 1/4 4130 plate to the top and out side of the arm with some gussets between the top and bottom. That way it would sandwich a 3/4x5/8 heim and i think more steering angle could be obtained by going with a 7" or 8" ram. If longs are good to 40 degrees i might as well use it. Plus i might be able to get some original 6 stud marlin arms and just tig the 4x4 labs blocks on my stock knuckles. Billet 6 studs Marlin arms with arp studs and double shear arms would be sweet. 

Its the knuckle thats the limiter not the birf, and 6 stud arms dont do you as much good as MC's 25mm stud upgrade. I know it sucks but there has been some tech on Pirate about it. Its was amazing to see a steering arm pin break in half and still have all 6 studs still in tact and unbent. I would never have belived it but its true the pin breaks before the studs. I'll see if I can find it and post here for you guys to see.