yep, we`ve had to with some, alignment of head to the block isn`t always exactly the same on every block/head combo,,, some rockers/head combos we`ve found (on other peoples engines) in combination with the small hole blocks have made for some serious yukkyness
but i warn about opening the cyl head holes up, it`s do-able with std valve roady stuff,,, but some big heads (like what we do) have huge ports that interfer with the pushrod holes so we sleave them to keep going bigger with port,,, so attempting to drill the push-rod holes in a head like that would cause a bit of anxt, to say the least
just have a good look & a good measure & make sure your cyl head alignment & push rod holes & push-rods & rockers are all set-up with "middle of the road" clearance,,, you only need to look carefully when assembling,,, if it`s all on the wonk then do some spacing &/or drilling
just be carefull
most of the rubbing pushrods (that i`ve found) have come from poor rocker spacing (side ways stuff) but then the worst combo is poorly aligned rockers/head/block with fat push rods & poor spacing with offset rockers added ontop of small hole blocks
we drill em if they`re looking suspect on the first dummy build.