I just recently traded for a 69 350. It too is the 300hp version per the block codes. The stamped block codes in front of the passenger side head and on the rear where the tranny/bellhousing bolts will tell you it's manuf date, plant and what vehicle series it came in.
re. 2 or 4 bolt. Theres only one sure fire way to know, you gotta drop the pan. You could try to run a scope up the oil drain but if it has an oil deflector/baffle that'll not help. Since my engine runs good and doesn't show any leaks that mystery will have to wait.
