problem with msd disributor wobbling

I know Ive been away for a while but its summer ,new built 360 , I am having trouble getting my timing to settle down , and it seem to do opposite of what I want it to . I set it at 7 degree"s advanced and some times it goes wacked on me going from 7 adv.to -8 brand new motor but 10 year old msd 6AL and distributor .
has any had this problem ? could my distributor shaft be bent ,it dropped right in , but seems to have picked up a slight wable or vibration and I cannot get my timing to set still.
tried new timing light , same results. So I was wondering if I could have a bad bushing or bent distributor shaft?? or does any 1 have just a msd 6Al non vaccum distributor that works correct I could try , rent from you , or buy if it works right to try totrouble shoot this problem or a good electronic mopar set up with a high perf. box and electronics you are willing to sell cheap . I have a electronic distributor so I just need the rest of it or all at the right price if you just stepped up to a new MSD please contact me asap if you have a good electronic set for sale ,a 6 al no vac distributor or have an insight to my issue I am having . need asap . please don't waist my time and I wont waist yours with junk parts
THANKS ALL I have been away a little bit with health problems and now car troubles , but know we can get it figure out here .
hope all your summers are going gr8 . please lend a hand if you can . Jon