Simple. GM had alot of the 307s to get rid off and they needed to meet CAFE (fuel mileage) requirements. The 307 became the standard engine in all b-body wagons circa 1987 IIRC.
Not sure on the heads.
www.442.com and read the Olds FAQ.
Then come go to yahoogroups.com and come join us on the 77-90 B-Body email list.
