GMC Heads and blocks interchange. There are four heads that I know of, the 412. 819, 477 and a large port H head used on the 302 or possibly 270. I dont know enough to tell you that the large port head would benefit a 248 or 228. The experts here can discuss advantages or pros and cons.
Piston type is best matched to the head casting codes. One head best matched for dome top pistons and the other for flat top pistons.
Check this out:
http://www.oldgmctrucks.com/Photos/GMC_Numbers.htm
