You need AMC oil through the pushrod lifters, and coresponding pushrods of the right length. Your best bet is to buy EQ 318 b magnum replacement castings, which have the LA bolt pattern. Use Olds rocker studs if you want to run sbc 1.6 rockers. If you go with stock rockers the stock parts are ok. If you go sbc rockers Comp makes guide plates, but be sure and check for proper pushrod clearance. WHEN BOLTED TO THE HEADS . Mine came slightly warped and i had to file ALL of them. I am not sure but you might need to block the oil passages in the block deck surface that feed LA head rocker shafts.
The 318b heads flow very well with a little bowl work. The spring pockets can be cut .100 deeper to allow higher lift cams. These 318b heads make better power and tolerate more compression than LA castings i believe. I made 504 hp with 318b mildly worked(bowls only 2.02 int 1.60 ex) on a 408.