How much HP is needed to gain about 4 tenths?

[82 GT]

Ok, as some of you may or may not know from last year, I was trying to break into the 12's but ran into a proverbial "brick wall" at 13.3@104mph.
I have a NOS system to install this winter but would like to run 12's N/A and was wondering about how much HP I would need to crack the 12's......30-40?

Now, my best 60' time was a crappy 1.92(with M/T slicks).
Do you think a torque converter change alone will do it?
I currently have a 2400-2500 stall converter but I want to get a 3500 stall to help my 60' times.
I was also considering 1.7 roller rockers as well.
I don't know if my new fuel system will gain me any E.T(haven't been to the track since then).
What do you guys think would be my best bet to get that extra 3-4 tenths?
My ultimate goal is to run mid 11's with the nitrous and mid 12's N/A
I'm open for suggestions.