is there a way to change the 305 tbi to tpi or will it not work and if so will it increase the horsepower difference between the 2

 

Yes, there is: http://www.thirdgen.org/newdesign/tech/tbitotpi.shtml

You will probably see a slight gain in HP, I'd guess 5 HP, but not much. The reason for this is because the stock cylinder heads and camshaft that came on the 305 TBI motors are junk and are still going to hold you back.

 

I definatly wouldn't bother for reasons already stated. The TPI wasn't all that much better as an intake, it was really the heads and cam that were a little better in the l98.
Look into the 350tbi swap out of a cop car caprice, get the motor, build it a little while it is out of the car, and learn to tune chips. It will cost more but will give you a lot more hp. You're going to have to make a custom chip going from tbi-tpi anyway if you want the maximum gain out of it.

 

Talkin about tuning your own chips is there software and hardware available for this?

 

I really don't know much about doing chips, as I have never done one. You do need a laptop (it doesn't have to be a good one, any old laptop will do it) that you plug into your car so you can see exactly what is going on. Then you pull your chip out (or burn a new one if you have two), whipe it, and reprogram it with the laptop.
I think their is actually a new program you can use which basically lets the laptop act as an ecm to make changes more easially, or possibly even on the fly.
As I said I don't know much so don't take anything I say as an absolute truth, go read up on it.

 

My car is a 91 R(eally)S(low) 305 that has been converted to TPI. I have ta say that it runs alot better than a TBI.

 

My dad has converted a few TBI's to TPI. You can re-pin the stock TBI harness to work with the TPI computer. Its not something a beginner can do but it is possible to do in your garage if you're mechanically inclined.

On my dad's 92 Camaro with the TBI engine, it made 158 HP and 220 TQ. After swapping to the TPI intake and computer, it made 178 HP and 290 TQ. Putting in a 91 TPI camshaft added another 9 HP but the TQ was the same.

 

That 92 should have been making 170/255 from the factory, it's probably just showing it's age.
It will give it some power but not as much as the tpi cars had, for example the 92 z28 with a 305 had 205/270 or 230/300 depending on the option. If you are looking to get a little bit more out of the motor and stop modding then the tpi might be worth it. The stock one isn't good for a high hp motor so don't plan on getting too much power.
The first thing I would do if you havn't already done so is headers and an exhaust, maybie an open element. That is usually enough to get an 103 to about 200hp.