Difference In Year Of273 Intake/heads

I'm afraid I have to disagree with the opinion that the 920 casting is the best for a 273. I've found that the '68-74 casting #675 is better for a street motor. It has less crack problems and you can use pump gas without any pinging. If you use the ones off a '72-4 model year, you also get the benefit of hardened seats.