a ? about a b-303 cam and stock heads

[lon ramsey]

i want to put a b-303 cam in my 88 gt using my stock heads.the proformance shop told me the only thing i need is a shim set for the rockers so i got them.a few other people told me i dont need them.will it go right in ?do i need the shims??the lift on the cam is .480.if someone did the samething im doing email me at [email protected] and let me know please.thanks,Lon