Better Performance Output

Raul said
Should I try advancing it again. I don't think I must've moved it more than a couple of degrees. It really shouldn't backfire for that , should it?

Sure, why not?
If the mixture in any cylinder lights off before the intake valve is completely closed, what's going to happen? (check out those links in last paragraph here, especially this one.)

Raul said
I knew I had to retard it to get rid of the pinging, so I backed it down very little. Pinging was gone, but it runs slightly rough and has that backfire up the carb especially when cold.

So why go back to what you know is no good? Keep going 'til its better (or gets worse in some way). Signs of too little advance will be that it acts sluggish and runs hot.

Raul said
I noticed it was pinging in 5th gear, where it never had before the switchover. I was going to see where the timing marks were lined up but when I put the timing light on it, it was not reading anywhere on the timing mark scale.

Too many unknowns. Was this done with vacuum advance? Plug the vac advance for base timing measurement. When done, if the base timing was anywhere from 12 to 20 BTDC, make sure the the vac advance hose is attached to the timing port on the side front metering block.
If the timing marks only go to 10 degrees, you'll need to add marks using a timing tape.