HAC was probably not on your BJ70.
Pressurized cooling system might be from poorly seated head gasket - then again, might not be. It is possible for pressure to be in there and no head problem to exist. The surfaces need to be really clean and dry, and prepared to the right smoothness (need to be a little rough, not polished) when the gasket is put into place.
Even with a bad gasket, cracked head etc... a 3B will run if there's fuel, glow (or enough heat), and a starter that's cranking it over decently. I've seen these engines start and run with water pouring out the exhaust from a cracked head, water fountaining out of the rad etc.
Check to make sure that you have fuel getting to the injectors - crack a line near the injector and crank it over - if you get little spurts of fuel coming out, then you probably have fuel.
The fuel control rod can be removed (from EDIC motor to inj pump) and the Injection pump will default into the run position.
Pull your glow plugs and glow test them with a battery or decent sized battery charger (10A will do it nicely). It is very common for the wrong ones to be installed or for them to be burned out. Don't fool yourself into thinking a resistance test is good enough - glow them and see how long they take to get a good red/orange colour near the tip.
~John