273 correct heads?

There's the #315 head for 64 and 65. There is also a # 080 head for those years. In 66 there was a #178 (early)
#234 (late) and also the late #920 head which was used late in 66 and into 67. In 68 when 273's went open chamber and hydraulic cam, they shared the #675 head with the new LA 318.
Which is why the #234 came on 67 model year 318's in trucks, motorhomes.