i have a 120y and i used to know your pain but then i found out what happens when your water jacket gets clogged btween cylinder no 2 and 3. anyway that aside. i stumbled across a datsun sunny with some front damage and to my surprise it was only the front left. the guy who owned it was a teenager and was given the car from his dad who had just rebuilt the engine and was great until he hit a small wooden pole sticking 2 foot out of the ground and about 2 foot in the griound with a concrete filler thus he wrecked the steering on the left but all the engine bay was fine so $150 later a bottle of a new oil filter plugs and air filter i was towing away my new engine. so total cost was $250 for engine, gbox, set of 13" chrome rims and a whole lot of bits and bobs from the engine bay. on top of that i stripped down my old motor and took the head manifold starter motor distributor. pretty much everything that i could for spares. so if you can find a cheap sunny go for it one thing i didn't do and im snapped about is the seats get the seats they are comfier than the 120y ones
so lets say you have $400- 250 = 150 go out and buy a 32/36 webber carby from a 2lt escort or cortina and a rebuild kit and you should walk away with enough cash for a carton or a tank of fuel