Demano, there's a lot of confusion on pinion angle. With a carbureted engine it's ideal to have the carb base dead level with the vehicle at ride height, and it was common for intakes to be machined with a nominal three degree forward tilt, meaning the tranny mount was dropped relative to the motor mounts to level the carb base. Now you consider a street rod running bigs & littles, and that three degree manifold tilt may still have the carb sitting back end high, messing with float levels. With EFI the engine doesn't care about the angles, but it's still common to have that nominal three to four degree downward tilt at the tailshaft. If you can, it would be prudent for you to get your engine & tranny mounted before you melt in the 4 link mounts, or like Ryan says maybe tack them good, then go back and weld them solid later. As was pointed out, the amount of linear adjustment to achieve a degree of tilt is not that big, but why not get it set pretty close to right as your zero point?