Just a quick SWAG here. First, the timing marks work the same for points as for HEI. No difference.
Second, if I had to guess, I'd say that the front carb was running lean and the prolonged high speed run caused it to burn the exhaust valve in the #1 cylinder.
I don't know for sure where your oil went...have you looked under the truck to see if there's a gooey mess there? How about the tailgate? Got oil spots on it? These things would indicate a leaking seal or gasket(s) somewhere. Another thing that running lean could do is burn a piston, which would cause the lower compression, smoking, poor performance and the blowby could cause the pressure in the crankcase to force oil out from every possible nook and cranny.
When you get the head off, have your machine shop check the #1 exhaust valve. If it's not leaking, then it might be time to tear it down and replace the burned piston (or possibly all of them) and rings.
How about posting a pic of the head when you get it pulled off?
