Need Input, Engine Noise

[Want2Run]

So recently swapped engines on my 85 c10, went to 468 cu in BBC (454 bored .60 over). It was broke in w Joe Gibbs break-in oil and currently running 15w-50 Joe Gibbs now. I went to take the truck for the first drive did not ever drive it before, just ran to time, make carb adjustments, and on and off the trailer for exhaust. Did not make it but a mile down the road started a loud popping noise, shut it off instantly, and towed it back to my garage. Oil is milky so I am thinking blown head gasket.. but seems quite abrupt as no problems ever before until now, any thoughts on what could be making the noise?

[Woodyboat]

I am not a pro-mechanic by any means. But I do know that milky oil is a sign of moisture that has gotten mixed in. And so, I think you're correct because a bad head gasket is really the only place where moisture could get in.

Has your coolant level changed?

Also, does the oil have any sort of coolant odor?

If not coolant odor, what about any hint of gasoline odor. I think that, if gas has gotten in there, that may give a similar symptom.

I'm surprised that others, who are more knowledgeable than me, have not chimed in.