Checked up on the skylark the other day and to my disdain i found slush in the radiator,so just in case worse comes to worse im putting out feelers for a decent 350 short blocks. also might go with the 455 or 430 if i can find the parts or something thats running.
my old 350, the rad was frozen solid with WATER, and the block was about 90% water and was slush. I'd say if your rad was just slush, you'll be fine. park it in a warm garage, drain the rad add about 70/30 mix of concentrate coolant and water, and let it warm up with the cap off, see what happens and watch for leaks and check the oil constantly. I did that, and my 350 was perfectly fine, worst it did was fry a belt because the water pump was frozen.