more slant six timing q's

Hello,
New to the forum!

I have a question regarding timing in my 63 Dart /6.

Some background on the car:

It's a 63 Dodge Dart GT convert. It has a reman and later model 225 in it. The orig older (3 freeze plug) motor gave up the ghost shortly after I bought the car--loud rod knock. My buddy who was a mechanic put in the remanufactured 5 freeze plug motor. It's just an autozone motor or something similar, bought as a long block, with the older components swapped over, except for a new 1bbl carb. It still has the older distributor with points too.

Anyway, right after we got it going, I had to move away with it due to a military reassignment, so no more help sorting it out from my friend, but it ran very strong.

The issue was a lot of pinging from too much advance. It did have a heck of a lot of power though. Using a timing light, I finally figured out that it was off by a gear tooth on the distributor. Well, the dist. was put right, and timed to like 7 degress advance, but the car was now a dog. Even advancing it all the way didn't give me back the power that it had before, but did give me a little ping. Gas mileage also sucks. Any ideas on what's up with this?
Thanks in advance,
Brent

Here's the car, by the way: