Water fitting in on each log, other fitting out from each log goes to the front of the engine in to each head, the two lines out of the thermostat housing go to fitting to each snail port out. Normanly its suggested the lowest port gets the water in the other port out to heads in. Actually they will work either way, make a neater installation and less hoses all over the place. Their are pictures on Glen -l that will show I am sure someone here has one.

Or can I reverse it and put water from the jet to rear bottom of log and have it exit the front of log to the heads? And then from t-stat to snails. Will this work?

Or can I reverse it and put water from the jet to rear bottom of log and have it exit the front of log to the heads? And then from t-stat to snails. Will this work?

yes...But make sure you run a valve/gate right after leaving pump as a shut down/regulator. Like your olds, chevy needs some restriction of water....I have seen both either crack the head or blow a head gasket. I ran my olds at 180/200 in the summer. I also ran it wide open and cracked a head....