yep,panda based cars according to "museo seat" yes, but only few prototypes made by Emelba{ not Steyr-puch type of 4x4}, early cars before 1986, before "marbella" became a car name, "marbella" was one of the types of seat panda like seat panda terra, seat panda movida , seat panda marbella etc.
If you have complete panda 4x4 it will be an easy swap, you have everything you need. There are few things except the engine ,gearbox , suspension exhaust, all pipes and cables you would like to swap from rotten panda to marbella, like servo assisted brakes, sumpguard, few elements from under the car , strut copulas tops to accommodate panda 4x4 shocks etc
Some hints you can find in my topic about barts trekking 4x4 1200. Not every part from panda to bella will fit in 100%, engine mounts require to drill few new holes , central part of the prop can be attached in an "easy" way, just drill holes through the beams and floor, or in more professional way, by welding the "pieces" from panda 4x4, refers also to the sumpguard rear mounts. Some cables and wires are to short/ too long etc.
metal bits you need from the rotten 4x4 engine bay/ from under the car
servo brakes with supporting plate and all pedals, cables { clutch gas,etc}:
Consider changing the metal brake hoses to new ones, brake master cylinders are also different,
It is an easy swap, but there are hundreds small choises to make during the process, ask a lot on the forum and all'll be fine