Chevrolet Repair: Grooving of lifter bores, valve train components, ss 396

Question
Barry,need some help! '66 Chevelle SS 396. Had the 396 rebuilt at a local shop 4 years ago. Owner suggested to groove the lifter bores to supply oil directly to cam. Motor was/is noisy since startup. Rebuilder adjusted lash after 1 season didn't change. Hyd.cam @ approx. .550 lift. (1) Grooving of lifter bores bad ?(2)I have been checking valve train components and found stock length pushrods,tooshort?(3)Have bought measuring pushrods and solid lifter to check rocker arm geometry, .050 longer exh. and .020 longer intake seem to roll over center of valve better, but am concerned about valve to piston clearance. Any suggestions appreciated ! Block is '69 4 bolt

Answer
Grooving lifter bores was a trial and ERROR concept years ago by an engine builder with too much time on his hands!!  Can be fatal to oiling system and not recommended!! Note; I would either change blocks, or have new lifter sleeves put in.  Yes, rocker arm geometry is critical, and will NOT change lift measurement at valve after you get the pattern right!  NO Worries!!