Serious problems with new motor, please help

i just got my car going last night. the shortblock i got had 200 miles on it so basically brand new, had a fresh valve job done on my edelbrock heads, everything looked good and sounded good after getting it running. i had an exhaust leak, fixed that. went for a short drive, needed the rpm's raised at idle some. did that today and went to drive to a friends house. i made it there 7 city miles away with no problems. temp went up normally and sat at 170.

on the way home, my check oil light came on. my pressure was still good, so i drove the rest of the way (or so i thought) about 1 mile from my house i see steam coming from under the hood. i kill it, pull off and go to look. there is THICK white pasty crap coming out of the radiator. it is in my radiator, thermostat neck, ect. i checked my oil and it doesnt have any water or paste in it. no water in the radiator at all. just all the sudden went from normal running, to check oil, to overheating.

i let it cool down to about 140 and filled it with about a gallon of water i had and took off for home. it started to rise rapidly im temp again, so i shut it off and basically coasted home. i got about half mile, then it goes to residential area, i started it and went up to about 20 mph and shut it off again to make it home.

what the hell happened? i dont know if its a head gasket because the oil is still clean, but it apparently is low? it is so clean its hard to see on the dipstick, but it is right at the full line still.

any help is appreciated. i just busted my ass for 4 weeks to get this done and i drive it 13 miles and get a ****storm.

would just a head gasket cause THICK white paste? i mean, it is like yogurt.

is there anything else i can check first before ripping into it?

another thing that is weird i think? when it got hot and i went to look at it, i pulled the cap and the yogurt crap blasted out, then the lower radiator hose was moving around and flexing from pressure and moving water around in the radiator? is that normal with a head gasket?

like i said, my oil is clean still. oil in the autometer gauge line is clean.

thats exactly what i figured.

looks like ill be standing in the engine bay again tonight. i hate this damn car, but the engine sounded good in the beginning at least.

just for my information. i hope to never do this again, but is it normal for some bolts to loosen up when a head gasket goes?

my lower intake bolts were damn near finger tight, it only took like one turn with the ratchet and i could loosen them with my fingers. i went over them with the 8-16-24 ft.lb torque sequence when i installed it.

how thorough do i need to be cleaning the milky crap out?

i cleaned the cylinders good, but there is some in the channels next to the cylinders i cant really get. is that going to be ok?

everywhere else it went i can clean easier. radiator, intake line, ect. just need to know if i can leave the crap in those channels and be ok?