One nice thing about 64's is that you can put them on a 400 block and have a little more manageable compression(9.93 to 1) than the 16's. I like the 16's but I mix racing fuel in to accommodate the compression. The 64's are can be used with more available pump gas.
64's are hard to find cause they were the only D-port with 2.11/1.77 vlv's used on some 455's in 1970. 10.25 if memory serves. Usually go for big $ unless they dont know what they have.
I now have a complete set of #15s with hardened seats etc. with less than 1800 miles on them since complete rebuild. Replaced them with a set of #64s that I just bought. PM me if anyone is interested. These 15s need nothing and are complete and can be bolted on and good to go. They have also been tapped and have threaded studs as well...
