I was assuming it was 400ci.from what he was saying about getting caught with it because the limit in that class was 400ci.I do know that it had the block and head dubble O ringed and had a copper tube that ran down the length of the motor that was forever leaking water and had a bigger oil line going to the head or from it.never did figure out what was for.or the water either.but I do know that that was the strongest run and the best sounding 6cly.I have ever heard bar none...and as far as the head Im sure you could make it a two piece head and use an O ring or silicone to hold the water or a solid one for racing only,,what's your thut on that and i'm sore you could use say a HEMI style rocker??he will be home at 330 hopefully he will have good news on it.fingers crossed.........