seized slant six

Haven't done this in a while, but you can use diesel fuel, it will act similar to WD-40. Pull the plugs and fill up each cylinder. Let it sit a couple of days......... Drain it out, add a little ATF or MMO to each cylinder for lubrication then get a large breaker bar and try to bump/crank the motor and free it up.... If you can get it t crank then fully drain and clean it out. Add new fluids, spark plugs, wires, cap and rotor etc....... Change the fuel filter. Use some brake parts cleaner spray and flush out the carb. I find that the brake parts spray cleans out varnish and crud better than carb cleaner....... If you can get it to start then grab a timing lite and set that as well. Let it idle a while and warm up.... Once this is done you will also want to run a compression test to see where it's at condition wise...... Judging by the miles it will most likely be fine unless it seized due to broken internals. If it's just from sitting it can be saved. Clean out and flush the radiator, power steering, etc....... Basically all fluids. Drop the gas tank and clean that out as well.