I am still researching it also,but i think some lifters need the block clearanced for the link bars on the lifters and room to get them to drop in the bores.

and depending on the lift and springs..single/double/triple the heads may need machine work also. depending on how mild to wild the cam goes

and then there is the hydro roller lifters or solid roller lifters.

the lunati roller cam I used in the SB,used the comp 901-16 spring which is a single and drops on with stock seals,found that after i got the lunati springs and found it needed PC seals and machine work for double with damper.

so it be wize to do enuff research and homework with the BB swap,but in the long run it will pay off in performance and longevity done right the first time.