IMO B13 Sentra with VQ30DE-K (from 5th gen Maxima) swapped in.

Can be in the 200whp/200wtq area with bolt on's and it is fairly light for a V6 engine. You can also lower the mounting points on it to regain any handling lost by the "nose-heavy" tendancies of the swap.

With only 8K I would probably work on making a car handle incredible rther than making it as fast as possible. If you have a good chassis for 2-4K that leaves more than enough money for some of the best coilovers availible for the chassis and body reinforcement (seem welding, strut bars, subframe connectors).

Probably not on target but you have said that with all the replies.