70 dart 318/904/7.25

Ok so I've been going back and forth on what I should do. I've read a lot but the main thing I'm getting is you need to change this or that....I have a 318/a904/7.25 in my 70 dart. My question is how can I get the best performance out of what I already have. I would like a street/strip build. I already know the rear end I have is small and I would love to be able to put a 8 3/4 in the car but can't find/afford one right now. What is a good set up for what I have? I have the motor torn down and the trans is out. I've already started on a disc brake conversion on the front. Plan on replacing pitman, idler, end links etc....I need help knowing what combo of parts to get for the motor and trans. I do not care about fuel economy as this will not be a daily, but I still would like to be able to drive to work or to the track from time to time. Is it even possible to make a "fast/quick" car with the rear I have?.....I know people have probably asked or had the same problem as I am having, but every time I try and find something about it, people just say get a new motor/ rearend. Any help would be awesome!!!!

How fast is "fast" for you? I have a 318/904/7.25 and enjoy driving it almost every day.

My opinion: I would focus on keeping the car on the road with brakes, suspension, etc. while upgrading the 318 with parts that will transfer over to a hotter engine down the road.

Like Ignition upgrades and Cooling system. Then, when you drop that new rear and drivetrain you are good to go.