Welcome!
Okay --
I have the EZ EFI on my Nomad - 406 - 8 stack - so running the Multiport set up. I ABSOLUTELY LOVE this system - and migrated from the Accel Gen 7 stuff.
A couple of things to think about.
Make sure your motor has good - fairly steady - vacuum.... if it's really low and jumping all over the place -- you'll have "issues".
I had my cam ground on a 114* LSA to insure a good vacuum source.... it's critical.
FOLLOW THE DIRECTIONS --- when they say run the power source all the way to the battery -- they mean it. Heavy gauge high quality wiring with quality connectors... don't short cut this!
Tach signal is best taken DIRECTLY off the tach output of an MSD box - or similar brand.
As for the question of wet or dry intake --- everything is a trade off -- but for the street -- I doubt you'd know the difference between them... so if money is an issue - just run their conversion kit for the carb intake.... it works great and you'd be plenty happy. If you want "looks" etc -- then step up and spend the money for the multiport intake and throttle body. Again - doubt you'd feel or know the difference.
There are several threads on here regarding this EFI system -- including some videos of installs by members here....
RE: Your tank
Main thing to know.... you're pumping a lot of fuel THRU this system since it's a return type EFI.... you don't want to AREATE the fuel with the return line --- and you don't want to "uncover" your pickup on hard starts and cornering or going up steep grades! A suitable well planned fuel system is critical. Most guys use their existing supply line as the return line -- and install a new (larger) fuel supply line.
#2 --- there are threads on here about welding fuel tanks. I even started one myself. The key here is WASHING the tank with SOAP -- not just water (water and gas don't mix) and using he sniff test -- if it smells like gas there is gas and or fumes remaining.... and instead of killing yourself with exhaust pipe gas ---- use DRY ICE.... it turns into CO2 as it "melts" and that is an inert gas - it forces the O2 out... Read the thread on it.
Depending on the size of your current supply line (you do NOT want to go lean on WOT!!) you can use it as a supply and add a return - some guys run the return fuel into the fill neck of their tank.... If you have questions etc post up some pics in this thread and we'll all try to help you! Don't guess -- ask lots of questions -- there's GREAT people on here...