1985 G-20 Conversion Van Tune Up Questions...TIA

I recently bought a 1985 G-20 Conversion van that is in dire need of a tune up, but I don't have any info on the truck itself. I need to know what the
timing (At the balancer) marks are and where ZERO is on the indicator. Also I think (if I am correct about normal GMs) the first cylinder in the "H" 307 should be on the drivers side, but I am not sure if that is correct. One other thing on the whole "H" thing is it the eighth digit in the VIN as there is another 307 for this truck as far as I know and the sticker tells that it is a 5.0L. Further what should the firing order be on this motor if my homework is correct with the "H" VIN code.
Also is there anybody that has a "real" wiring diagram for the thing, and not the Hanyes manual style (meaning the Motor Manual type) I and trying to rewire a small annoyance that the former owner wired. It seems when ever the horn is blown or the power locks are used (in either lock or unlock) the wipers make a single stroke across the windshield.
Thanks for any help
Sincerely, Dark
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Chevy numbers the left bank as the odd number cylinders from front to rear, and the right side even numbers again front to rear. 1985 will be a 305 not 307, the 307 went away in 1973. The firing order is the same for all small block Chevy engines.1-8-4-3-6-5-7-2, the distributor turns clockwise. The notches on the indicator on the timing cover, the largest one is "0" or top dead center, if you clean the tab off you will find its marked with degrees. The smaller groove on the balancer is the one you use.
Whitelightning
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