Grey motor followers used to be a common conversion years ago but you dont see it much these days. The lifter bores in a A series need to be enlarged to accomodate Holden lifters and removing metal from a block weakens the block. I use new std lifters in my engines and dont modify them, lightening mini lifters makes them weak and prone to breakage. Holden Grey motors were a great old engine, one of my favourites, i have rebuit a few including a couple of hotties, they go very well when hotted up.
