Why not ask your mapper? If he knows more about the cams than you then surely he/she can advise on correct springs? You need to know the cam specs to decide on springs to avoid any binding issues.

Personally I would get a Cam/Follower/Spring combo set from whoever ground your cams to avoid any expensive issues.

If you do know them and need the followers and shims then Steve Slim will no doubt have the Arrow ones on the shelf.