i have a 283 with vortec heads with a 468/489 lift cam and i didnt even grind down my retainers. i havent had any problems with that. pushrods should be the same leingth.

i will be building a 383 or 406 with the same heads and i will be machining screw in studs, guide plates and thats about it. with that much lift and guide plates, you might have to drill out ur pushrod holes a bit. aka 1/2 in. drill. just make sure u have the right angle.

also, just sayin so you know, once you have machined the heads for guideplates.. (and screw in studs) you no longer need self aligning rocker arms.