The bowl shape and volume has varied a lot over years. Do you have the serial number for your engine? If so, I can look up what Cummins specs for it. Bowl design is often because of injector spray pattern or smog control. Most all 4B engines would have slightly wider bowls since the have 155 deg spray angle injectors. Also, a 4B may have a slightly higher compression ratio but that's not always true. You mention marine style bowls and that is a popular replacement type piston. True marine pistons would not be used in a 4B. They are low compression and wouldn't work well for that. Also, the 4B pistons are not the same as 4BT. They use different rings. You can use 4BT pistons in a 4B but not the other way around. Below is a photo of a 4B piston and it looks very much like the one in your photo. On the injectors, those need to be matched to your injection pumps for pop pressure. Stock injectors for you engine were possibly 4x.012 with 9mm tips. Cummins quit using those and any replacements from them are 7mm tip plus the sleeves you mentioned. 9mm heads had a bad reputation for cracks. Need to check yours. Those 5x.011 units are sort of odd size.
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