keeps fouling #2 and #8 sparkplugs

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Hi, i have a 71 c10 with a 350 v8, recently put in an hei distributor with new cap,rotor, spark plugs and wires. When I removed the old sparkplugs i noticed that #2 and #8 were prety bad , so i ran a compression test ,#3 had 60 psi, #7 had 90 psi and the rest have 120 psi, a few days later I blew out my 350 tranny, while removing it I saw that it was sucking transmision fluid through the modulator. It now has a 700r4 transmision from a 92 astro. But about every 100 miles it keeps fouling #2 & #8 sparkplugs, i take them out, clean them and it'll run fine till it fouls them up again, I dont know if its unburned gas or oil, any comments are greatly appreciated. Thanks