BMW M50 and M52 engines?

[carse]

Im looking to buy an e36 coupe as a track car, either a 320 or a 323 as i don't have much money to play with and am still at university but want to get out there and start somewhere, so i figured a lower powered rear wheel driver is not a bad place to start.

Just wondering if anyone could shed any light on what i've heard about the m50 motor. I've heard its heavy and a bit of a dog but thats only going from what i read on another forum somewhere. So basically, which block is better in your opinion? Is it worth going for a post 1994 car just for the update in the motor or not?

Thanks very much.

Sean