Not real sure what you're referring to on 2-4bbl adapter? But a normal gasket should not blow out, even with a backfire.
Gonna have to be more specific with regard to scantool, TBI is OLD school, OBDI, a scantool is fairly useless as a tool.
Most people use USB data cables, and TunerPro, or TunerCAT, some even still use WINALDL.
Somewhat recently ALDLDROID came onto the scene, for use on android devices, and there is bluetooth and regular data cables.
Vacuum advance is NOT needed, and should NOT be used with timing control enabled in .bin!
It should be locked out just like mechanical advance for timing control enabled systems.
Need to start with the basics.
Verify no vacuum leaks are present. Verify you have good fuel pressure.
What is the initial timing setting in the .bin? This is what yours should be set to.
You also need to do an initial setup of the throttle body.
Bill has a good write-up...
http://www.binderplanet.com/forums/inde ... ost-345737
Some systems/engines are picky, and while everyone likes to just slap things on and turn the key, there is a 'bit more to it.