Want to build a 77 360 suggestions please

What's gutless? What is your goal for the car? Let me explain. A 360 with a mild cam and 4bbl, if tuned properly, should be around 325 hp gross? So if this is "gutless", and you think adding 75 hp will go from "gutless" to "world beater", then I would step back and access. Is there a certain E.T. you are hoping to achieve that would make you happy? Tell us a little more....
I’m not sure what the condition of this engine is in, I was told
it was rebuilt 12,000 miles ago, not sure looking at the paint on the motor not sure that really happened or not.
The motor right now sputters and misfires when I get on it, checked the timing its at 12 degrees ideling at 900 rpm ??
I would like to get into low 13s with this car