i havent been doing this long but my first motor was a trail and eror 383. first 383 had 5.7 rods ground for clearence for a cam with a lift of .510. this year i put 6.0 eagle stroker rods in it clearence is there for cam .558 lift and can go more but as for block clearence depends on the block. i had to grind oil pan rails and grind some out of the bottom of the bore (piston skirt doest even come close to this area). but what ever u do 5.565, 5.7, 6.0 have the whole rotating assemby balanced
the longer the rod the broader the power curve correct me on this if i am wrong anyone but pretty sure