The distributor is an old mopar one. The big slotted spring was removed. Kept the other spring. Shortened the mech adv slots.
A 180 stat is really more suited for a street car. Better FE and emissions. The 160 at this point is doing nothing.
You may find that more timing is needed at idle and less at cruising speed.
Try hooking up a manifold vacuum gauge and advancing the base timing at idle for highest vacuum. I got to belive that with the xe268 and a dual plane intk, that 15 inHg is achieveable. And somewhere around 19 to 24 degrees for base timing. Then adjust the distributor so total mechanical is 34 to 35. To achieve the high amount of base timing, try using the vacuum advance connected from manifold vacuum.
Once the idle timing is good (the motor will cool down), adjust the idle mixture screws for best vacuum. if backing out the screws does not over richen the mixture (you will know if over rich because the vacuum will drop), then open up the idle jet by about 2 thou (drill out). Not sure what carb your using. So, I have no advice for modifying the carb.
Next thing to do, with veh in park, slowly increase the engine speed form idle (in about 100 rpm increments) to about 2500 rpm. If there is no sputtering, then you are good to go. If the engine skips or won't rev up smoothly, then it has too much timing and may be lean, especially if the exhasut manifolds get red hot. The vacuum advace may be adding 18 degrees, but with your quicker mech advance, 18 may be too much. the vacuum advance may need to be reduced to supply 10. Reduce the timing and try the rpm sweep again. You can move the distributor on the car before taking it out to modify anything. A good timing light (dial back) is also needed. If you think the timing is right, but still gets hot at cruise, then more fuel may be needed. Hope you had a chance to read some of the articles from automotiveu.com