What are a couple good superchargers for 84 T/A?

 

A Weiand 142 works great on a 305.
look here

 

How much power should I see after installing this? How much is it? And lastly, what all do I need to use it without difficulty?

 

about 40%@7PSi boost. follow the link above and read it.

 

In the above link the guy says to get Champion RV8C spark plugs, but it says theyre discontinued boat spark plugs according to google.

 

As difficult as an intake manifold swap. You may need some earlier 305 smog-pump pulleys bring the smog pump closer to the block or order the extra-long nose blower to clear the stock belt that reaches out to the water pump and crank.

 

do you have to makje any major modifications to fit a supercharger or will the stock internals cope with the added power??

 

They claim stock internals will handle the modest boost the kit provides. If you change the pulley and add more boost, your motor will go bye-bye.
I have found the kit to require a little messaging to get the parts to fit. We had to grind on the pulley snout and the termostat housing to get the blower to aline with the holes in the manifold.
Forget about calling Holley for assistance, those guys are useless. They will put you on hold for half an hour then tell you they never heard of that problem and that they will look into it.
Fact is Holley bought a bunch of companies and now don't know know $hi* about the products they are currently selling.
Thats what happens when companies monopolize things.
Do we need ANTITRUST laws again?

 

Still available at CTC as far as I know. Yes they are used in boats.
A AC delco R42T is the same or very close. Not "TS" There is an equivelent NGK plug to the RV8c. its basicly a non-projected tip about 3 heat ranges cooler than the stock chevy plug. The number
is BR6FS. All, still available, according to my "Magic Squirrel".

They aer actually a common used plug. If you don't see them on display at your local auto parts store go to the parts counter and ask.

At any rate you want to use a non-projected tip plug that is a few heat ranges cooler than a "stock plug" for the heads you use on your blown street motor.