You need to identify which mopar distributor you have. Some have the mallory advance mechanism, easy to adjust, doesn't require disassmbly. The old style mopar ones require the distributor to be torn down.

Look below the top plate and turn distributor shaft looking for a pair of T-15 torks head screws and a pair of small windows with a tab sticking up through it. If it has that style, it's a mallory set up. Loosen the torks heads and close the window up.

You can easily whip up some keys for desired advance. There is some info here

https://board.moparts.org/ubbthreads/show...amp;Search=true

Old style, weld the plates.
http://www.moparmusclemagazine.com/techa...em/viewall.html

I tend to weld the slot area closest to the shaft center.

Mr gasket makes a light spring kit #927 IIRC if you want to change the curve.