Are these heads good? casting 3973487. These were apparently stock heads on the 72 30 LT-1 engine.

I would say they're the best of the large chamber (76cc) factory SB heads...some came with 2.02/1.6, some with 1.94/1.5 valves...most big valve versions were also machined for screw in studs.

I ran a set of the 487X heads that 2.02/1.6 valves on a 350 with a generic .443/.465 214/224* cam, Performer intake and a set of 1 5/8" headers. It was a nice torquey engine.