"Still debating on rebuilding the 289 with upgrades or go for a 302. Thinking hard on converting to a 5 speed. "
I did a 260 at first in my 65, but could not get the power from it that I wanted. I had a 95 mustang GT that would not pass smog with all the aftermarket parts on it. I pulled the engine and 5 speed changed it to a carb setup and did the swap. If you do go with a 302 and 5 speed I would recommend a donor car. I got the 95 for $1500, sold the body for $800 and the EFI for $200. In the end I was only into it $500 and it allowed me to pick any parts I needed before I let it go. The only things I had to change to the 5.0 HO was to drill the timing chain cover for a front dip stick, swap the oil pump pick up, swap oil pan and order the 5 speed transmission crossmember kit.