Did some research on capsules trying to find common ground between APBA and SFI capsule requirements. Does not exist. APBA Reinforced capsules with a cage and canopy requires a bottom hatch and SFI cages require so much x-bracing you couldn't put in a door in the floor big enough for a gerbil. On the other hand nether would require a capsule in any kind of Comp Jet anyway. So If it had one which rules would apply. Or would any rule apply?
Drag boat, no problem, SFI capsule. They require like three production prototypes to be sent to them for testing. Basically you provide them with $30k worth of brand new capsules and they check them out for you and return them in a trash bag. Of course you have to pay them for the privilege.
Circle Boat, not sure yet. I haven't looked thoroughly through all the rules but I think you can use one of about four different capsules anything from a reinforced tub to a full caged, canopy covered, self contained job with said hatch in the floor.
So unless you build two separate boats or get APBA to approve of using a SFI Capsule you could not take a circle boat to an NJBA event and run it in the drags.