Head code should be one letter followed by 3 numbers. It could be I037, which would be September 3, 1967, but I thought they skipped the letter "I" for casting codes. If they are #16 heads with a cast date of I037, those are 1968 small-chamber heads, usually found on the higher compression engines. They are desirable heads.
The block casting date should also be one letter, followed by 3 numbers. Your code (C3198) has one too many digits. Maybe post pics so we can help.
The engine code is actually the two-letter (WT) stamp. If the date codes verify that you have a 1968 block, that WT code with the 16 heads is 360HP 400 combo (for manual transmission applications).
Pontiac started stamping blocks with the last 6 digits of the vehicle VIN in 67/68. The 6 digit number above the WT (093737) is the last 6 digits of the vehicle VIN in which this engine was installed.
I have no idea what the "86138" means. There should be a block casting number in that same area. If this is a 68 400/360HP block, the casting number should be 9790071.
Pics would help.
Did you order the PHS document package for this car? That would tell you what it originally came with.
Also, there is a lot of great info here: Wallace Racing-Drag Racing Pontiac powered Firebirds,Trans Ams and Dragsters
Congrats on the new car!