want to make some budget power, find a 96-01 ford explorer in the junkyard. buy the top end of the motor get the heads and the intake. or if you have high miles take the entire motor.
the motor features GT40 style heads(93-95cobra) and a gt40 style intake, the only thing that is lacking over a real cobra motor is the cam and roller rockers. add a new cam and some roller rockers you can get close to your 750$ budget
say 400$ for the motor
150$ for a new cam
150 for some roller rockers
and about 50$ for new gaskets(you would have to swap you original oil pan,timing cover, distributor and oil filter boss on to the explorer motor)
this setup will be an easy 300HP