I remember now reading in hotrod or another magazine that one way reduce the octane requirement of a higher compression motor is to add a EGR valve,I have a 66 390 and a 65 352 that both have around 10 to 1 compression and I would like to try adding a EGR valve before changing heads. Did ford make a 4 bbl intake or did or still do the aftermarket make 4 bbl intakes for EGR equipped FE motors,could a older intake be drilled so that a EGR carb spacer be used?,changing a intake is a lot easier then changing the heads. Jeff