whats better odb1 or 2 i need help????

ok i own a 94 bmw 325 is. wich use to be a m50 obd1 engine... without the vanos system.. the second engine i recentley got is out of the same same yr but its was automatic with obd2 and with vanos.. and also a secondary plug with brain of some sort or idk what it is but i took it with the engine. and on the other side by the fuse box connection theres a secondary conntection too. .. so should i stick with the new harnes or old????.i have the new harnes on now everything pluged in but cant get it to start. so should i go back to obd1 and switch all the sensors. but how would i do that with the vanos system there and the knock sensors or dont watch up. .so please anyone give advice . my car deserves to run freely on the road again! Damnit its been to long. so help any advice will do!!!