this one has me stumped

[supradaddy0803]

To start I have checked and the knock is coming from the top end not the bottom. Ok when I first got my car it ran like crap it is a 87 n/a 5spd so i decided to tcheck a few things one being the timing when i got the chance to actually check it (i work out of town a lot) i noticed it was about 3 degrees before which yes is real slow I know now it is right dead on 10 degrees and now it has a preignition knock of sorts under load about 2000 to 3000 RPM it gets a destinctive knock from the topend too light of a sound to be from the bottom plus to quiet to be a rod knocking sounds more like valves hitting or a wrist pin maybe number 2 or 3 so i pulled the distributor to check the pickups on it shop manual says between g1 and g-, g2 and g-, and ne and g- needs to be 140- 180 ohms mine is 225 to 230 which it calls bad i am gonna check the timing belt but I am sure it is on but my question is is this a normal problem and if so can i fix the distributor pickups without buying a new one. I have good oil pressure about 6 at idle and over 40 at higher RPM only mods done to the car are a K&N filter and a HKS dragger catback. Also I replaced the distributor rotor because it was loose and looked like it had been hitting the points and it has a new cap. any help would be greatly appreciated and it may take me a few day to get back to you with answers because I work a lot out of town I have just run out of ideas and would really like to not have to rebuild if it comes to it.