Went to look at a 1972 Ford Econoline Van. The engine is either the 351 or 302 (owner unsure, in 72 it would I believe it would have been a 302, but may have been changed.) A previous owner had it converted to fuel-injection using an FiTech kit. Started fine, seemed to run well. Did a low speed test dive around the neighborhood, and idled it, probably on 15-20 minutes total run time. Noticed coolant coming out of the overflow tube (there is no overflow tank). When I revved the van, the amount increased. I repeated this cycle a few times. There is a digital temperature display with the fuel-injection kit, and it showed the temp in the 166-172 range. I checked the radiator about 15 minutes after shut-off. Coolant level was to the top. I had checked the coolant before when it was completely cold, and the level had been about an inch lower. Coolant looks clean. There was some debris, but didn't look like oil. Looked to be some old radiator gunk (radiator is old). So, are there explanations for this other than a head-gasket? Or does that seem the most likely?