What to do with your car is of course your choice. Do you need it for everyday transportation,or can you lay it up for a few weeks while tweeking things out? If you are serious about putting in some power,I'd locate and install the 8 in. rear first,as it would be an easy weekend swap. As to what engine, I'd say go with what you can get for the best price. Even a 2.3 can be made into a tire burner,with cam ,carb, headwork and a good header. Hank
