Picture shows a L168 dated,#48
casting head, not a '68 model #16
. Big valve #16
's being factory installed on '69 model V8's is disinformation that made it into the most common copied code book, that happened nearly 30 years ago. Have owned several early '69 model WT's, all had original date matching #48
's. Same experience with hundreds of other long time Pontiac collectors. '69 YS coded 400 blocks eceived #62
On this convert, body tag shows an 11C body tag build. Not sure if Baltimore plant had a body bank. Even if Baltimore had a body bank, looking at a time window of a painted body having to set in the body bank 6 weeks, minimum, so it could be united with an original engine with L168 dated heads. With no UAW strike, to throw things off, would surmise the 4 week later cast #48
heads are not original, but were picked up & installed at a later date on the SR fitted short block.
The block casting number is cast on the block flange area coming up from the oil filter hsg mtg pad. A fully ground off & stamped "071' 400 block casting have never ran across. Have had in my hands, many original "2506"s both original use, and SR's. Once the #48
1988 casting 400 blocks began being cast in June of 1970, SR 4 bolt 400 blocks had all 6 digits ground off & was replaced by the applicable 400 4 bolt casting number. Similar deal with 428's. On the block in the above '69 convert, it would be of interest to know the alphanumeric casting date by the distribution hole.
Congrats on the save! Being in MN, you are in a hotbed of GTO restorer/enthusiasts! Need select condition hard to find original parts, GTO JOHN used to post on this board. He as well as a good friend further west, both are deep stocked on '69 parts & '69 projects. Need their numbers, can fwd them.