MK3 fuel pump isnt good enough so you need MK2 k-jet under-car pump. MK2 pump can fit I think as the MK3 filter housing fits the MK2, just MK3 has only 2 studs under there not 4. you could fit MK2 tank and lift pump, or I guess the MK3 main pump could be plumbed in, i recon excess will just be returned to tank.
then airbox will need some tweaks to fit, shouldnt be hard. perhaps corrado or passat 9a airbox would fit better, just swap kr metering flap onto it as 9a metering unit totally different.
last hurdle is the cat, the kr will kill it as its not designed for cat operation in mind. however since engine is old enough to not require it you can legally decat the car. however onus is on you to prove to mot tester age of engine, vw might be able to supply a letter if you can get the engine code off the block.