Winnebago Adventurer Chevy 454 7.4 possible blown head gasket?

[TXbound]

The coach is a 97 Adventurer the engine is Chevy 454 7.4 L Vortac block with 95k original miles I live in it, having an issue that might be a blown head gasket or worse and I really need to deal with it before the next bad storm that may force us to evacuate. Check Engine light not on, can't run OBD2 says its either not connected or the ignition is not on, first thing thar comes to.mind is bad ECM? Bad Sensors? 1st noticeable symptom is white smoke from the manifold, no trace of sweet smell, I took video of it I'm trying to figure out how to share it (no smoke or sweet smell from rear exhaust, only droplets of water, (moisture in the fuel lines is common here, I add a bottle of HEAT and seams to keep it in check) 2nd is had a back fire 1x but started up rough, high idle to almost stall till it warms up than it revs high and than adjusts to close to normal idle. It hasn't had a tune up in years, there is a presence of oil on the engine cover spark plugs manifold side. No sign of coolant leak, I did the trick to take the coolant cap off before starting and as soon as I started it in less than a minute it overflowed bubbling, I understand that could be a sign of a blown head gasket. Any thoughts on what's going on and what I can do to prevent any potential further damage? Thanks