You need a checking pushrod first, once you get it you can use it to see how long exactly your pushrods will need to be to order them. Second thing is which lifters are you using, solid flat tappets, hydraulic flat tappets, solid rollers or hydraulic roller lifters? They can all have different cup depths and some have different body lengths, especially in the roller lifters I sell both Mantons and Smith Bros, PM me if you need help on getting what you need