Is it unusual to see these without air injection holes in the heads and are they any good other than a date code for a restoration ?
C8-H heads, as well as C7-A's and C6-R's (and a couple other '66 heads) were made in four iterations: 8-hole with air holes, 8-hole without air holes, 14-hole with, 14-hole without. Ports and valves are the same throughout in each casting #. All forms are somewhat common; C8's more so because they were used in four production years (thinking about it, maybe no 14-hole for '70 and '71?).
14-hole castings are correct for all shock tower applications, either 2V or 4V applications. The only 8-hole C8's that would be desired for a resto would be the '68-'69 428 Police cars, as they did not use CJ heads, or LTD and Marauder type cars.
All FE heads are good. They are what you make of them. Roundabout the turn of the century I talked to a guy on the phone who had a lightened 67-68 Mustang fastback running the 10.90 Super Street index with a 428 topped with ported C8-H heads.