If you want the barrel body ones, 55's are as high as they go, the 60 lb ones are the pencil type, either way they are interchangeable, but the pencil type are way better
you can use the siemens deka/mototron injectors on a 5.0, they are almost the exact same height. Buick guys have been changing from the bosch barrel type because it is a disc injector (poor desing but flows alot, cant handle much pressure past 45) to the siemens deka injector. We keep them on the shelf in dearborn if you want me to send some to roseville so you can compare side by side.